owners manual

owners manual
MODEL 5908
owners manual
3 Before You
4 Safety
5 Tools, Supplies
and Required
6 Anatomy of
Your Slayer
7 Quick Start:
Getting Up
to Speed
8 Gluing the Tires
and Decorating
Your Slayer
9 The Traxxas
TQ Radio System
16 The TRX 3.3
Racing Engine
31 Driving Your
32 Basic Tuning
38 Maintaining
and Storing
Your Slayer
40 Advanced Tuning
2 • Slayer
Thank you for purchasing a Traxxas Slayer. The Slayer is designed to
simulate the speed and excitement of full-scale Pro 4 short-course
race trucks. 4WD Short Course Racing brings together the most
horsepower and the most suspension travel for incredible side-byside, fender-banging racing action. Engines scream at the redline as
dirt and rocks roost from all four tires. Only the fastest, most powerful
trucks dare to compete! The Traxxas Slayer Pro 4WD brings the sound,
smell, and excitement of Pro 4 short-course racing right into your
own backyard.
The TRX 3.3 Racing Engine is the most powerful engine of its size ever
available in a Ready-To-Run truck. Advanced engineering and design,
along with thousands of hours of testing, puts the TRX 3.3 in a class
by itself. Each part of the TRX 3.3 - from the air filter on the slide
carburetor, to the tip on the dyno-tuned exhaust system - has been
carefully engineered to provide maximum power over the broadest
rpm range.
We know you’re excited about getting your new Slayer on the road,
but it’s very important that you take some time to read through
the Owners Manual. This manual contains all the necessary set-up,
break-in, tuning, and operating procedures that allow you to unlock
the incredible performance and adjustment potential that Traxxas
engineers designed into Slayer. Even if you are an experienced
R/C enthusiast, it’s important to read and follow the procedures
in this manual. Slayer contains new technologies in the engine,
suspension, and transmission operation that you may not be
familiar with. Pay particular attention to the fuel and break-in
requirements for the engine. The advanced design of the TRX
3.3 Racing Engine has a special break-in procedure that has been
developed and proven to produce the best-performing engine
possible. Using traditional or old-fashioned procedures could
reduce engine performance and longevity.
Traxxas Support
Traxxas support is with you every step of the
way. Refer to the next page to find out how to
contact us and what your support options are.
Quick Start
This manual is designed with a Quick
Start path that outlines the necessary
procedures to get your model up
and running in the shortest time possible. If you are an
experienced R/C enthusiast you will find it helpful and fast.
Be sure and read through the rest of the manual to learn
about important safety, maintenance, and adjustment
procedures. Turn to page 7 to begin.
Slayer is made to be a complete package that starts with the highest
level of engineering; a professionally produced DVD to acquaint
you with the starting, racing, and maintenance procedures; and is
equipped stock with the most powerful Ready-To-Race® engine
available. We want you to feel confident that you own the bestperforming truck in the market and that it is backed by a team
of professionals who aim to provide the highest level of factory
support possible. Slayer is about experiencing total performance and
satisfaction, not just with your truck, but also with the company that
stands behind it.
Thank you again for going with Traxxas. We work hard every day
to assure you the highest level of customer satisfaction possible.
We truly want you to enjoy your new Slayer!
Before You Proceed
Carefully read and follow all instructions in this and any
accompanying materials to prevent serious damage to your
model. Failure to follow these instructions will be considered
abuse and/or neglect.
Before running your model, look over this entire manual and
examine the model carefully. If for some reason you decide it is not
what you wanted, then do not continue any further. Your hobby
dealer absolutely cannot accept a model for return or exchange
after it has been run.
Technical support is available Monday through Friday from 8:30am
to 9:00pm central time. Technical assistance is also available at
Traxxas.com. You may also e-mail customer support with your
question at [email protected] Join thousands of registered
members in our online community at Traxxas.com.
Warnings, Helpful Hints, & Cross-References
Throughout this manual, you’ll notice warnings and helpful hints
identified by the icons below. Be sure to read them!
An important warning about personal safety or avoiding
damage to your model and related components.
Traxxas offers a full-service, on-site repair facility to handle any
of your Traxxas service needs. Maintenance and replacement
parts may be purchased directly from Traxxas by phone or online
at BuyTraxxas.com. You can save time, along with shipping
and handling costs, by purchasing replacement parts from your
local dealer.
Special advice from Traxxas to make things easier
and more fun.
Do not hesitate to contact us with any of your product support needs.
We want you to be thoroughly satisfied with your new model!
If you have any questions about your model or its operation,
call the Traxxas Technical Support line toll-free at:
1-888-TRAXXAS (1-888-872-9927)*
Refers you to a page with a related topic.
*Toll-free support is available to U.S. residents only.
1100 Klein Road
Plano, Texas 75074
Phone: 972-265-8000
Toll-free 1-888-TRAXXAS
Traxxas U.K.
P.O. Box 1128
Winterbourne, Bristol
Phone: 44-117-956-1002
E-mail: [email protected]
Entire contents ©2008 Traxxas.
Traxxas, Ready-To-Race, ReadyTo-Win, Slayer and ProGraphix
are trademarks or registered
trademarks of Traxxas. Other
brand names and marks are
the property of their respective
holders and are used only for
purposes of identification. No
part of this manual may be
reproduced or distributed in print
or electronic media without the
express written permission of
Traxxas. Specifications are subject
to change without notice.
Slayer • 3
Safety Precautions
1 2 3 3+ 4 5
All instructions and
precautions outlined in this
manual should be strictly
followed to ensure safe
operation of your model.
This model is not intended
for use by children (minors)
under 16 years of age
without the supervision
of a responsible and
knowledgeable adult.
All of us at Traxxas want you to safely enjoy your new Slayer. Operate
your Slayer sensibly and with care, and it will be exciting, safe, and fun
for you and those around you. Failure to operate your Slayer in a safe
and responsible manner may result in property damage and serious
injury. The precautions outlined in this manual should be strictly
followed to help ensure safe operation. You alone must see that the
instructions are followed and the precautions are adhered to.
Important Points to Remember
Slayer is very fast! The Slayer is intended for experienced users with
a high level of skill. The TRX 3.3 Racing Engine is extremely powerful
and may require skilled driving to maintain control. Children under
16 years of age and inexperienced drivers should not operate the
Slayer without the supervision of a responsible and knowledgeable
(experienced) adult.
Model engine fuel is dangerous and highly poisonous.
Always follow all directions and precautions printed on the fuel
container. Model engine fuel is poisonous to humans and animals.
Drinking the fuel can cause blindness and death. Handle with care
and respect.
Models require detailed
setup, and/or maintenance
procedures with required
support equipment.
Previous experience with
radio controlled models
is mandatory. These
models are capable of very
high speeds and require
an even higher level of
skilled driving control.
Model engine fuel, especially when in a fuel dispensing bottle, may
look like a cool drink to a child. Keep all fuel out of the reach of
children at all times. Do not place fuel containers on the ground
where children can reach them while you are driving.
Model engine fuel is flammable. Never allow smoking, sparks,
heat or flame in the presence of fuel or fuel vapors.
The engine, brakes, and exhaust system may become extremely
hot during use. Be careful not to touch the parts, especially when
refueling or stopping the engine.
Prolonged exposure to the engine exhaust can be harmful. Avoid
breathing the engine exhaust. Always run your Slayer outdoors,
in a well-ventilated area. Never run the engine indoors.
Do not operate your Slayer at night, or anytime your line of sight to
the model may be obstructed or impaired in any way.
Never operate your Slayer in crowds of people or busy pedestrian
areas. Slayer is very fast and could cause injury to those unaware of
its presence. Keep small children at a safe distance away from the
operating area.
4 • Slayer
Because Slayer is controlled by radio, itBELOW
is subjectTEXT
interference from many sources beyond
your wants
control. Since
interference can cause momentary loss of control, always allow
a safety margin in all directions around your model to prevent
Choose the Model That is Rig
The engine can be loud. If the noise makes you uncomfortable,
wear ear protection. BeNo
of your neighbors
previous experience
with radio
models is re
running your model early
in the
or late inofthe
a minimum
maintenance, or sup
Most importantly, use good common sense at all times.
Previous experience with radio controlled models is recom
Models require a higher level of setup, maintenance, or s
Previous experience with radio controlled models is mand
models are capable of high speeds, requiring experience
Models require detailed setup, and/or maintenance proce
support equipment.
Previous experience with radio controlled models is mand
These models are capable of very high speeds and requi
level of skilled driving control. Models require detailed set
nance procedures with required support equipment.
For Expert Drivers Only. This product is capable of extr
and acceleration! It carries our highest skill level rating an
for expert drivers only. Experience with nitro-powered rad
models is required!
Tools, Supplies and Required Equipment
Your Slayer comes with a set of specialty metric tools. You’ll need to purchase other items, available from your hobby dealer, to operate and maintain your model.
Supplied Tools and Equipment
For more information on radio
system batteries, see Use the
Right Batteries on page 11.
Shock wrench
8mm slipper clutch wrench
Glow plug
1.5mm “L” wrench
Turnbuckle wrench
Suspension multi-tool
2.0mm “T” wrench
2.5mm “L” wrench
4-way wrench
Antenna nut
2.5mm “T” wrench
Recommended Equipment
These items are not required
for the operation of your
model, but are a good idea to
include in any R/C toolbox:
• Safety glasses
• Thin, hobby-quality
cyanoacrylate instant tire
glue (CA glue)
• Hobby knife
• Side cutters and/or needle
nose pliers
• Philips screwdriver
• Soldering iron
Extra oiled air filter set
(pre-filter and primary filter)
Suspension tuning
shims and hollow balls
Required Tools and Equipment
(sold separately)
10% quart - #5010
20% quart - #5020
33% quart - #5030
10% gallon - #5060
20% gallon - #5070
33% gallon - #5080
Traxxas Top Fuel® Power Plus™
see page 20
After-run oil to protect
the engine from corrosion
12 AA alkaline batteries
Small flat-blade screwdriver
for tuning (1/8 inch blade)
NiCad or NiMH
7.2V battery pack
Air filter oil
Traxxas part #5263
NiCad or NiMH battery charger
Traxxas part #3030X shown
Fuel dispensing bottle
(Traxxas part #5001)
Slayer • 5
Anatomy of the Slayer
TRX 3.3 Racing Engine
see pg. 19 for details
Throttle Linkage to
Throttle/Brake Servo
(below filter)
Exhaust Header
Roll Hoop
Driveshaft (Half Shaft)
Nerf Bar
Body Mount Post
EZ-Start Plug
Hex Hub
Axle Carrier
Access Plug
(for two-speed adjustment)
Pivot Ball
Suspension Arm
Push Rod
Air Filter
Skid Plate
Brake Tension
Pipe Hanger
(under chassis)
Tuned Pipe
Fuel Line
Fuel Cap
Disc Brake
Fuel Tank
Antenna Mount
On/Off Switch
Pressure Line
Engine Shut-off
Receiver Box
Fuel Cap
6 • Slayer
(under chassis)
Oil Shock (Damper)
Toe Link (Turnbuckle)
Spring Pre-load Adjuster
Steering Servo
Quick Start: Getting up to Speed
The following guide is an overview of the procedures for getting your Slayer running, from opening the box to breaking in and tuning your
engine. Refer to the pages indicated for details on each step. Look for the Quick Start logo on the bottom corners of Quick Start pages.
1. Read the safety precautions on page 4
For your own safety, understand where carelessness and misuse could
lead to personal injury.
2. Charge the EZ-Start battery pack • See page 24
The EZ-Start requires a fully charged 7.2-volt battery
pack (sold separately).
3. Install the receiver batteries • See page 11
Slayer requires 4 AA alkaline or rechargeable batteries
for the receiver (sold separately).
4. Install the antenna • See page 12.
Use the antenna nut wrench to install the antenna mast in Slayer.
5. Decal and Install the body • See page 8
You will need to use the body during break in, so it’s best to apply any
additional decals before you use the body.
6. Install batteries in the transmitter • See page 11
Slayer requires 8 AA alkaline or rechargeable batteries
for the transmitter (sold separately).
7. Install the EZ-Start battery • See page 24
10. Range test the radio system • See page 15
Follow this procedure to make sure your radio system works properly at
a distance and that there is no interference from outside sources.
11. Fill the fuel tank • See page 21
Use your fuel-dispensing bottle to fill the tank.
12. Connect the EZ-Start to the model • See page 24
Learn the proper way to use the EZ-Start electric starting system.
13. Start the engine • See page 26
Learn to use the correct starting procedure for your TRX 3.3.
14. Break-in your engine • See page 26
Follow the break-in instructions exactly to ensure the
best-performing, longest-lasting engine.
15. Tune your engine • See page 28
Learn how to set the fuel mixture needles for optimum
engine performance.
16. Drive your Slayer • See page 31
Install and connect a charged 7.2-volt battery pack in
the EZ-Start controller.
Learn to use the two-speed function on your truck, along
with important driving precautions.
8. Turn on the radio system • See page 14
17. Maintaining your Truck • See pages 38-39
Make a habit of turning the transmitter on first, and off last.
The Quick Start Guide is
not intended to replace the
full operating instructions
available in this manual.
Please read this entire
manual for complete
instructions on the proper
use and maintenance of
your Slayer.
Follow these critical steps to maintain the performance of your
Slayer and keep it in excellent running condition.
Look for the Quick Start
logo at the bottom of
Quick Start pages.
9. Check servo operation • See page 15
Make sure the throttle, shifting, and steering servos are
working correctly.
Slayer • 7
Decorating your Model
Always wear safety glasses
to prevent glue from
splattering into your eyes.
The acetone in fingernail
polish remover will remove
excess glue from your
Tire Gluing
Applying The Decals
The factory tires on your Slayer are already glued to the rims. The tires
must be glued to the rims to prevent the rims from spinning inside
the tires. The instructions here are provided to show you how to glue
replacement tires to the rims in the future. Use CA tire glue available
from your local hobby dealer. You can glue the tires without removing
the wheels from the truck. For clarity, these instructions show the
process with the wheels removed.
The main decals have already
been applied to your Slayer. The
extra decals provided are die-cut
for easy removal. Use a hobby
knife to lift the corner
of a decal and remove it from
the backing.
1. Remove a wheel from Slayer
using the larger 8mm end of the
glow plug (universal) wrench.
For best results while
gluing, clean the bead of
the tires and the grooves of
the wheels with denatured
alcohol before applying
glue. This removes any
mold release agent residue
from the tires and wheels,
providing a better bond.
2. Use your thumb to push the
side of the tire away from the
rim. Place one or two drops of
CA glue into the opening and
release the tire. Capillary action
will draw the glue around the
bead of the tire.
3. Repeat step two at four or five points around the rim, until the tire
is completely secured to the rim. Turn the rim over and repeat the
process for the inside of the rim/tire. Repeat for the other 3 wheels.
4. Reinstall the wheels.
8 • Slayer
Carefully position the decal over
the desired location and press
one side on the body. Pull the
decal tight and use a finger to
gradually smooth out any air
bubbles as you apply the decal.
Look at the photos on the box
for typical decal placement.
The Traxxas TQ Radio System
Your Slayer is equipped with the TQ radio system. The TQ is a 2-channel system that provides up to a quarter mile range and control for up to three
servo outputs.
TQ Transmitter
Slayer Wiring Diagram
Throttle Neutral Adjust
4-cell Battery
Steering Wheel
Throttle Trim
Steering Trim
Slayer has a provision for a
built-in charging jack so you
do not have to remove the
battery pack from the model.
The wire for the charging
jack is supplied with the
factory harness, and is stored
inside the receiver box. It is
not installed in the charging
jack to prevent inadvertently
charging alkaline batteries.
Never use the charging
jack with the 4-cell battery
holder. The charging jack is
for optional rechargeable
5-cell nickel metal hydride
(NiMH) batteries only. See
page 11 for more details.
Servo Reversing
Power Switch
Battery Compartment
Channel 3 (not used)
Channel 2
Channel 1 (not used)
Channel 1
Power Indicator
Slayer • 9
The Traxxas TQ Radio System
Radio System Terminology
Learn terms related to
the TRX 3.3 Racing Engine
beginning on page 18.
Please take a moment to familiarize yourself with these radiosystem terms. They will be used throughout this manual.
5-Cell Pack – Another term for RX Pack or rechargeable receiver pack.
The RX pack is made up of five rechargeable NiMH battery cells and
is used in place of the 4AA batteries in the model.
Channel - The 27 MHz frequency band is divided into 6 channels
so that up to six models can be operated simultaneously. Each
channel is referred to by its flag color and channel number, as
shown below.
Part no.
Clearing your frequency - A routine, verbal check to make sure
nobody else in your area is operating on the same channel.
Always clear your frequency by calling out your channel number
before operating your model. Wait or move to another area if your
channel is already being used.
Crystal (X-tal) - The plug-in device that determines which channel
the radio system will operate on. For each channel, there are two
crystals, one for the receiver and one for the transmitter. Of those
two crystals, the one marked with the lower number (.455 MHz
lower) must be inserted into the receiver.
Frequency band - The radio frequency used by the transmitter to
send signals to your model. All Traxxas RTR models operate on a
27 MHz frequency band.
mAh – Abbreviation for milliamp hour. A measure of the capacity of
the battery pack. The higher the number, the longer the battery
will last between recharges.
10 • Slayer
Neutral position - The standing position that the servos seek when
the transmitter controls are at the neutral setting.
NiCad - Abbreviation for nickel-cadmium. The original rechargeable
hobby pack, NiCad batteries have very high current handling,
high capacity, and can last up to 1000 charging cycles. Good
charging procedures are required to reduce the possibility of
developing a “memory” effect and shortened run times.
NiMH - Abbreviation for nickel-metal hydride. Rechargeable NiMH
batteries offer high current handling, and much greater resistance
to the “memory” effect. NiMH batteries generally allow higher
capacity than NiCad batteries. They can last up to 500 charge
cycles. A peak charger designed for NiMH batteries is required for
optimal performance.
Receiver - The radio unit inside your model that receives signals
from the transmitter and relays them to the servos.
RX Pack - RX is a common abbreviation for the radio receiver and
items associated with it. RX Pack denotes the optional rechargeable
battery pack used to power the radio system in the model. It is
available as Traxxas part number 3037.
Servos - Small motor units in your Slayer that operate the throttle and
steering mechanisms.
Transmitter - The hand-held radio unit that sends throttle and
steering instructions to your model.
Trim - The fine-tuning adjustment of the neutral position of the
servos, made by adjusting the throttle and steering trim sliders on
the face of the transmitter.
The Traxxas TQ Radio System
Installing Transmitter Batteries
Installing Receiver Batteries
Your TQ transmitter uses 8 AA batteries. The battery compartment is
located in the base of the transmitter.
The radio receiver in your model uses 4 AA batteries.
The battery holder for the receiver batteries is
located underneath the battery cover. The battery
cover can be identified by the on/off switch.
1.Access the battery compartment by removing the
4x12mm and 4x20mm buttonhead cap screws
from the chassis. Swing out the nerf bar just far
enough to clear the battery compartment cover.
2.Remove the battery holder and install 4 AA
alkaline batteries. Make careful note of the battery
polarity by comparing against the diagrams in the
battery holder.
3.Insert the battery holder into the battery compartment.
4.Reinstall the battery cover and secure with the screws.
1. Remove the battery compartment door by pressing the tab and
lifting the door up.
2. Install the batteries in the correct orientation as indicated in the
battery compartment.
3. Reinstall the battery door and snap it closed.
4. Turn on the transmitter and check the power indicator for a
solid red light.
If the power indicator light flashes, then the transmitter batteries are
weak, discharged or possibly installed incorrectly. Replace with new or
freshly charged batteries. The power indicator light does not indicate
the charge level of the RX Power Pack installed in the model.
To prevent losing control of your model, it is important to stop at the first
sign of weak receiver batteries to avoid losing control. Visible warning
signals include sluggish steering response and shortened radio range.
Traxxas TRX Power System (optional)
The optional Traxxas TRX Power System can be purchased
separately to power the radio system in the Slayer. Benefits
include the economy of a rechargeable 5-cell nickel metal
hydride (NiMH) battery pack that replaces AA alkaline
batteries, and increased voltage for dramatically improved
servo performance. The TRX Power Charger (Part #3030X)
is a peak detecting unit that will charge the RX Power
Pack (Part #3036 flat pack or #3037 hump pack) in about one hour. The peak
detection circuitry automatically shuts off the charger when the maximum
charge has been achieved. The TRX Power Charger also includes a 7.2V adapter
for charging 7.2V EZ-Start batteries. The TRX Power Charger can operate on
either AC or DC power. A special wiring harness for Slayer (Traxxas part #3034)
that includes a handy external charging jack is required.
The optional DC car adapter (Part #3032) features a tangle-free,
extra long wire and integrated fuse. The long charging cord
allows the model to remain outside the car while charging.
Caution! Never charge batteries in an enclosed car interior
or while driving. Never leave charging batteries unattended.
Monitor them closely.
Traxxas’ integrated TRX Power System is the easiest way to add the power and
economy of rechargeable batteries to your Slayer. Consult your hobby dealer
for purchasing information.
Use the Right Batteries
Your transmitter uses AA
batteries. Use new alkaline
batteries, or rechargeable
batteries such as NiCad
or NiMH (Nickel Metal
Hydride) batteries in your
transmitter. Make sure
rechargeable batteries are
fully charged according to the
manufacturer’s instructions.
If you use rechargeable
batteries in your
transmitter, be aware
that when they begin
to lose their charge, they lose
power much more quickly than
regular alkaline batteries.
Caution: Discontinue running
your Slayer at the first sign of
weak batteries (flashing red
light) to avoid losing control.
If the power indicator doesn’t
light red, check the polarity
of the batteries. Check
rechargeable batteries for a
full charge.
Slayer • 11
The Traxxas TQ Radio System
Setting up the Antenna
Spray a little window cleaner
on the antenna wire to make
it easier to push through the
antenna tube.
Don’t shorten the length of
the antenna wire. Its length
is tuned to the frequency
band; cutting it could
severely shorten the radio
system’s range.
1. Locate the black antenna wire that exits the receiver. Route the
receiver antenna through the radio box lid and then slide the
antenna wire through the antenna tube.
Antenna Tip
2. Secure the lid to the radio box with a body clip and then slide an
antenna cap over the end of the antenna tube while leaving the
antenna wire exposed.
3. Insert the antenna tube into the mounting post. Slide the crimp
nut over the antenna tube and screw it onto the antenna post.
Use the supplied tool to tighten the crimp nut on the post just
until the antenna tube is securely in place. Do not over tighten.
Antenna Tube
Don’t push the transmitter
antenna down from the
top. Pull it down from the
bottom, one segment at a
time, to prevent binding and
kinking the antenna mast.
12 • Slayer
The Traxxas TQ Radio System
TQ Radio System Controls
TQ Radio System Adjustments
In addition to the electronic throttle and steering trim controls, your radio
system features throttle neutral adjustment and servo reversing switches.
Throttle Neutral Adjustment
The throttle neutral adjustment is
located on the transmitter face and
controls the forward/brake travel
of the throttle trigger. Change the
adjustment by pressing the button
and sliding it to the desired position.
There are two settings available:
50/50: Allows equal travel for both acceleration and braking.
70/30: Allows more throttle travel (70%) and less brake travel (30%).
50/50 is the required setting for Slayer with the TRX 3.3 Racing Engine.
Electronic Throttle Trim
The electronic throttle trim located on the face of the transmitter
adjusts the neutral (center) point of the throttle servo when the
servo is at rest. This control has been preset for you at the factory.
If necessary, adjust the control so that the carburetor is at idle, and
the brakes are not applied (the model will roll freely). Do not use the
throttle trim to raise or lower the engine idle speed. Make the idle
speed adjustment on the carburetor.
When the engine is running,
don’t use the throttle trim on
the transmitter to adjust the
engine idle speed. Instead,
use the idle speed adjustment
on the carburetor.
Electronic Steering Trim
The electronic steering trim located on the face of the transmitter
adjusts the neutral (center) point of the steering servos when the
servos are at rest. Adjust this control to make the model drive straight
with no steering input at the wheel.
Servo Reversing Switches
The servo reversing switches are located on the front of the
transmitter, next to the on/off switch. Moving a switch reverses the
direction of the corresponding servo. Each switch corresponds to a
channel, as shown below. For example, if you turn the steering wheel
to the right and your front wheels turn left, you would move the
channel 1 switch to correct the servo direction. It may be necessary
to adjust the corresponding trim control after moving a switch. The
default position for the servo reversing switches is shown.
Default Setting
Slayer • 13
The Traxxas TQ Radio System
TQ Radio System Rules
Remember, always turn the
TQ transmitter on first and
off last to avoid damage to
your Slayer. Never turn the
radio off while the engine
is running.
Always have the transmitter and receiver turned on before you
start the engine. Never turn the radio system off while the engine
is running. The on/off switch in the model only turns the receiver
on and off. It does not turn off the engine.
Each time you prepare to run your Slayer,
you must clear your frequency to be sure
no one else in the area is using the same
channel as you.
Always use new or freshly charged batteries for the transmitter, and
make sure the receiver batteries are fresh. Weak batteries will limit
the radio signal between the receiver and the transmitter. Loss of
the radio signal can cause you to lose control of your Slayer.
There are six possible channels,
numbered 1 through 6. Each is
represented by a color. Look at the
crystal plugged into the back of your
transmitter to determine which channel
your truck is assigned to.
Always turn your TQ transmitter on first and off last. This
procedure will help to prevent your Slayer from receiving stray
signals from another transmitter, or other source, and running out
of control.
Always turn your
receiver on second.
Then start your engine.
Always turn your
transmitter on first.
14 • Slayer
The Traxxas TQ Radio System
Using the TQ Radio System
The TQ Radio System was pre-adjusted at the factory. The adjustment
should be checked before running the model, in case of movement
during shipping. Here’s how:
6. Operate the throttle trigger on the transmitter and check for rapid
operation of the throttle servo. When the throttle trigger is pulled
back, the carburetor should open (slide moves out). When the
throttle trigger is pushed all the way forward, the brake should lock.
1. Fully extend the chrome antenna mast on the transmitter and
turn the switch on. The red indicator light on the transmitter
should be solid red (not flashing).
7. Once adjustments are made, turn off the receiver on your Slayer,
followed by the hand-held transmitter.
2. Turn on the receiver switch in the model. The switch is located in
the top of the radio compartment.
Before each running session with your Slayer, you should range-test
your radio system to ensure that it operates properly.
3. Position Slayer so that its front wheels are off the ground.
1. Turn on the radio system and check its operation as described in
the previous section (Using the TQ Radio System).
Don’t attempt to operate
your Slayer if there are any
problems with your radio
system or radio interference
at your location.
Range-Testing the TQ Radio System
4. Turn the steering wheel on the transmitter back and forth and
check for rapid operation of the steering servo. Also, check that
the steering mechanism is not loose or binding. If the steering
operates slowly, then check the receiver pack to make sure it is
fully charged.
5. When looking down at model, the front wheels should be
pointing straight ahead. If the wheels are turned slightly to the left
or right, slowly adjust the steering trim control on the transmitter
until they are pointing straight ahead.
2. Have a friend hold the model with the engine off.
3. Make sure your transmitter antenna is fully extended, and then
walk away from the model with the transmitter until you reach the
farthest distance you plan to operate the model.
4. Operate the controls on the transmitter once again to be sure that
the model responds correctly.
5. Do not attempt to operate the model if there is any problem with
the radio system or any external interference with your radio
signal at your location.
Slayer • 15
The TRX 3.3 Racing Engine™
Traxxas strongly discourages
changing or modifying any
part of the TRX 3.3 Racing
Engine. Old tech tips and
tricks that may have boosted
the power of other engines
could seriously diminish the
performance of the
TRX 3.3 Racing Engine.
There’s more advanced
thinking, development and
testing in the stock parts
of your TRX 3.3 Racing
Engine than in many
aftermarket manufacturer’s
performance parts. The TRX
3.3 Racing Engine is already
the most powerful engine
in its class and may not
benefit from average, lowtech, aftermarket bolt on
performance items.
The TRX® 3.3 Racing Engine is the next generation of TRX nitro
power. The larger displacement and advanced porting generate
class-leading horsepower while still maintaining the TRX Racing
Engine characteristics of broad, linear power delivery and ease of
tuning. Focused engineering and rigorous testing have yielded
unprecedented power and uncompromising performance that turns
ready-to-run into Ready-To-Race®.
The TRX 3.3 Racing Engine takes a total-system approach. Each
part of the engine, from the air filter to the exhaust tip, is carefully
engineered to work in harmony with other engine components. Each
part complements the next, to extract maximum power. The TRX 3.3
Racing Engine is designed to be tolerant of variations in tuning, and
to run successfully through a wide range of variable atmospheric
conditions such as changes in temperature, humidity, and altitude.
In order to get the longest engine life and keep the TRX 3.3 Racing
Engine in top running condition, it is very important to perform
regular routine maintenance. The number one cause of premature
engine wear and failure is lack of care and maintenance!
The TRX 3.3 Racing Engine is manufactured to exacting tolerances
and requires a specially-designed break-in procedure to accomplish
the final precision fitting of the internal engine components. It is very
important that you follow the new break-in procedure as closely as
possible to achieve the best performance and longest life from your
TRX 3.3 Racing Engine. Engine break-in will take between one and
two hours. Old style break-in procedures, such as idling the engine on
the bench for several tanks of fuel or simply running the engine with
a very rich fuel mixture for the first 4 tanks of fuel, will not achieve the
best results. Follow the easy steps in this manual.
Dirt is the worst enemy to your engine. A clean air filter is absolutely
critical for long engine life. Due to the high performance nature of
the TRX 3.3 engine, a tremendous amount of vacuum is created to
move a large volume of high velocity air through the carburetor. This
model is equipped with a two-stage high performance air filter which
requires that the pre-filter stage be cleaned and oiled every hour of
operation, and the primary filter be cleaned and oiled every 3-4 hours.
An extra pre-lubed air filter set has been provided with this model to
encourage you to maintain the engine’s air filter.
16 • Slayer
Perform after-run maintenance on the engine to prevent corrosion
from building up on the internal engine components. The fuel
naturally attracts moisture and corrosion can build up very quickly
inside the engine if it is not prevented.
A few minutes spent before and after each time you run your model
will allow you to enjoy it for a long time to come. Read on for more
exciting details about your new engine.
The TRX 3.3 Racing Engine
Air Filter
Glow Plug
Idle Speed
Head Protector
Slayer’s fuel tank is
equipped with a built-in
sintered bronze fuel filter.
PowerTune™ Head
(Cylinder Head)
EZ-Start® Drive Unit
EZ-Start® Motor
Low-Speed Needle
Fuel Intake
Air Intake
Engine Mount
Throttle Arm
Clutch Bell
Glow Plug Wire
Tuned Pipe
EZ-Start Plug
Ground Wire
Positive Wire
Negative Wire
Fuel Line
Shut-off Clamp
Fuel Tank
Slayer • 17
The TRX 3.3 Racing Engine
You’ll find these Nitro R/C engine terms throughout this section
of the manual.
18 • Slayer
.15 - .15 or “15” refers to the displacement of the engine. The TRX 2.5
Racing Engine is .15 cubic inches or 2.5 cubic centimeters (cc). The
name “TRX 2.5” is derived from the cc measurement.
.20 - .20 or “20” refers to the size of the engine. The TRX 3.3 is .20
cubic inches or 3.3 cubic centimeters (cc). The name “TRX 3.3” is
derived from the cc measurement.
ABC - Abbreviation for aluminum, brass, and chrome. Refers to
engine construction that consists of an aluminum piston that slides
in a chrome-plated brass sleeve. The TRX 3.3 uses ABC construction.
Air filter - The air filter sits atop the carburetor and prevents harmful
dust and dirt from entering the engine. Dirt ingestion is the number
one cause of premature engine failure so the engine should never
be run without the air filter in place.
BDC - Bottom dead center. The bottom-most position of the engine
piston stroke.
Break-in - Break-in is the procedure for running a brand new engine
according to specific instructions. This correctly prepares the engine
for normal running. The break-in procedure can be different for
different makes of engines. Follow the Traxxas directions for breakin exactly.
Carb - Abbreviation for carburetor.
Carburetor - The carburetor atomizes (mixes) the fuel with the air
so that the engine can burn it. There are two types of carburetors;
slide carbs and barrel carbs. The TRX 3.3 uses the superior slide
carburetor design.
Clean-out - Cleaning-out is a condition that occurs when the engine
is accelerating and the fuel mixture becomes sufficiently lean to
allow the engine to continue into its upper rpm power band. It
is usually characterized by a noticeable decrease in blue exhaust
smoke and a dramatic increase in engine speed.
Combustion chamber - The combustion chamber is machined into
the bottom of the cylinder head. This is where the glow plug ignites
the fuel. The shape of the combustion chamber is designed to
promote more efficient burning of the fuel.
Connecting rod - The connecting rod transfers the piston motion
to the crankshaft. The TRX 3.3 Racing Engine uses a “knife-edged”
connecting rod. The aerodynamic, sharpened edges allow it to
“slice” through the pressurized air/fuel mixture inside the crankcase.
Crankcase - The engine’s “body” that contains all of the running
mechanical components.
Crankshaft - The main shaft of the engine that holds the
reciprocating assembly.
Cooling fins - The cooling fins are milled into the cylinder head and
crankcase and cause heat to be drawn away from the engine. Heat
is removed when it dissipates into the air passing across the cooling
fins. It is important to keep the fins clean of dirt and debris for
maximum cooling efficiency.
Cylinder head (head) - The finned aluminum part on top of the
engine that is responsible for dissipating most of the engine’s heat.
The combustion chamber is machined into the bottom of the head.
Dyno - Abbreviation for dynamometer. A precise piece of testing
equipment that accurately measures engine power and torque
output over the engine’s entire rpm range.
EZ-Start - Traxxas on-board electric starting system. The system
consists of a hand held starter control unit and an on-board
gearbox with an electric motor to spin the engine.
Fit - Usually refers to the fit of the piston and sleeve. If the fit is tight,
the piston will feel very tight at top of the sleeve (top dead center),
and the engine will have good sealing and compression. If the fit
is loose, compression will be low and both the piston and sleeve
should be replaced.
Flame-out - Occurs when the engine stops running at high rpm.
Usually the fault of an excessively lean fuel mixture or glow
plug failure.
Fuel - (10%, 20%, 33%) The TRX 3.3 must have model engine fuel to run.
Traxxas Top Fuel® Power Plus™ is recommended. Fuel is sold in quarts
and gallons from hobby dealers. The 10%, 20% and 33% labeling refers
to the percentage of nitromethane contained in the fuel.
Fuel mixture - The ratio of fuel to air as determined by the needle
settings of the carburetor.
Fuel tubing (fuel line) - The thick silicone tubing that carries fuel
from the fuel tank to the carburetor.
Glow plug - The glow plug is located in the cylinder head at the top
of the combustion chamber. It contains an element that glows red
hot when voltage is applied. When the engine is being started,
the heat from the glow plug ignites the fuel mixture and starts the
combustion process.
Glow plug driver - This tool clips onto the glow plug and supplies the
required voltage to light the glow plug element. It is also called an
igniter. EZ-Start equipped engines do not require this separate tool.
Header - The aluminum tube that connects the exhaust system to the
engine exhaust port. The length and diameter of the header must
be carefully selected to extract the most power from the engine.
The TRX 3.3 Racing Engine
High-speed needle (HSN) - Adjusts the carburetors fuel/air mixture at
high throttle openings.
Idle speed - The speed (rpm) the engine runs at when the
transmitter’s throttle trigger is at neutral.
Idle speed screw (ISS) - Located on the carburetor body. This screw
adjusts the idle rpm of the engine.
Lean - A running condition where the engine is not getting enough
fuel (for the available air). Symptoms include engine overheating,
or the engine runs for a short time and then stalls, particularly at
high speed. This is a dangerous condition that should be corrected
immediately or it can ruin your engine.
Leaning the mixture - Turning either the high-speed and/or lowspeed needle(s) clockwise to decrease the amount of fuel the
engine receives.
Low-speed needle (LSN) - Needle valve that controls the fuel mixture
at low throttle openings.
Needle valve - Valve consisting of a tapered needle that closes
against a corresponding seat to regulate fuel flow.
Nitro - Abbreviation for nitromethane, a component of model engine
fuel that improves fuel combustion and power output. Nitro also
refers to a class of R/C powered by model engines instead of electric.
Nitro content - The amount of nitromethane used in the fuel. Usually
measured as a percentage of the total fuel volume. Traxxas engines
are optimized to use 10-20% nitro. 33% nitro may be used for
Nitromethane - Nitromethane is a component in the fuel that
increases power from the combustion process up to a point.
Engines are generally optimized to use a range of nitro content for
the best power.
O-ring - Rubber “O”-shaped ring used as a sealing gasket.
Pipe - Abbreviation for the tuned exhaust pipe on a nitro engine.
See “Tuned Pipe”.
Piston - The piston is the internal engine part that is attached to
the upper end of the connecting rod and moves up and down
in the cylinder sleeve. The precise fit between the piston and the
sleeve creates a seal that allows the engine to have the required
compression for combustion.
Port - Ports are openings in the sleeve that allow atomized fuel to
enter the combustion chamber and burned exhaust gases to exit.
The shape and location of the ports are a large factor in controlling
the engine timing and power output.
Pre-filter - The outer air filter element in a two-stage air filter. This
provides the first level of air filtration for the engine. The majority
of dirt and debris will be stopped by this filter. Clean, re-oil, and
replace this filter after every hour of run time. Always use both the
pre-filter and primary filter.
Primary filter - The inner air filter element in a two-stage air filter.
This provides a second level of air filtration after the pre-filter
removes the majority of dirt and debris. Clean, re-oil, and replace
this filter after every 3 - 4 hours of run time. Always use both the
pre-filter and primary filter.
Priming - Manually causing fuel to move from the fuel tank up to the
carburetor. This is sometimes necessary after the engine has been
sitting for a long period of time and all of the fuel has drained back
to the tank. On a Traxxas model this is done by holding your finger
over the exhaust tip for one or two seconds while the engine is
Punch - A term that refers to how quickly the model responds to
throttle input or how quickly it accelerates.
Rich - A running condition where the engine is getting too much
fuel for the available air. It is better to run an engine slightly rich
to increase engine life. Excessively rich mixtures cause the engine
to have sluggish performance with exaggerated blue smoke and
unburned fuel coming from the exhaust.
rpm - Abbreviation for revolutions per minute (how many times the
engine crankshaft spins in a minute).
Sleeve - Internal engine part that contains the piston. The precise fit
between the sleeve and the piston creates a seal that allows engine
to have the required compression for combustion. The sleeve in a
TRX engine is made of brass and is then hard-chrome plated.
Slide carburetor - The throttle on a slide carburetor closes and
opens by sliding a barrel in and out of the carburetor body. This
type of carburetor is preferred for performance use because it
provides a less restrictive “straight-through” air path than the barrel
carburetor design.
Stall - When the engine stops running, usually due to an incorrect
fuel mixture setting or running out of fuel.
TDC - Top dead center. The top-most position of the engine
piston stroke.
Tuned pipe - The tuned exhaust pipe usually consists of a speciallyshaped metal or composite chamber with baffles that is designed to
enhance the power output of the engine.
Wear-in - Fitment process that occurs during engine break-in where
internal engine parts develop an even more precise matched fit
through actual use under controlled circumstances.
WOT - Abbreviation for wide-open throttle.
Slayer • 19
The TRX 3.3 Racing Engine
The Fuel
DANGER! Model engine fuel
is poisonous to humans
and animals. Drinking the
fuel can cause blindness
and death. Handle with
care and respect. Keep
it out of reach of small
children at all times! While
driving, do not leave your
fuel dispensing bottle on
the ground where a child
could have access to it.
Follow fuel label warnings.
Use the Right Fuel
It’s imperative that you use the correct fuel in your
TRX 3.3 Racing Engine for maximum performance
and engine life. Traxxas Top Fuel® Power Plus™
should be used to ensure correct engine
lubrication, performance, and ease of tuning.
Top Fuel is the only fuel which is
100% certified for use in Traxxas engines.
Traxxas Top Fuel is made with just the right
balance of natural and synthetic lubricants to allow excellent
throttle response and the best top-end performance, without
sacrificing long-term durability.
You may use 10%, 20% or 33% nitro-content fuel. Try to use the
same percentage all the time, avoid switching back and forth
between fuels. We recommend that if you break in your engine on
20% fuel that you stick with that percentage. If you do move to a
higher or lower percentage, make sure you readjust your fuel mixture
to compensate (see below).
Choosing a Nitro Percentage
A commonly asked question is “what is the difference between 10%,
20%, and 33% fuels?” Increasing the nitro in the fuel is almost like adding
extra oxygen to the combustion process. It burns more efficiently,
improves combustion, and delivers more power. When increased nitro
is used, more of the other fuel components are then required inside the
combustion chamber to maintain the perfect air/fuel ratio. Therefore,
overall fuel mixtures need to be richened slightly (on the high speed
needle, about 3/4 of a turn counterclockwise when changing from 20%
to 33%, about 1/2 of a turn counterclockwise when changing from 10%
to 20%). This allows greater fuel flow through the engine and promotes
cooler running, even at the maximum lean settings.
20 • Slayer
If 33% improves power, then it seems that the highest nitro content
available (beyond 33%) should always be used in the engine. In reality,
there are practical limitations. Engines are designed to run best within
a range of nitro percentages. How the engine is ported, the size of the
combustion chamber and other factors determine how much nitro can
be efficiently used in the engine. The TRX 3.3 Racing Engine responds
exceptionally well to a maximum of 33% nitro, returning cooler temps,
more power, and a smoother throttle response. For those who want to
run higher nitro, 33% Top Fuel is the optimum nitro percentage for the
TRX 3.3 Racing Engine. Increasing the nitro beyond 33% can introduce
the need for engine modifications (ports, head shimming, etc.) to avoid
starting and tuning difficulties. There are limits to how much nitro an
engine can effectively use to make more power. Lower nitro percentages
have their own advantages. Nitro is an expensive component in the
fuel so 10% nitro blend is more economical for the sport user. 10% also
provides greater latitude with the needle settings for easier tuning.
When using Traxxas Top Fuel, using higher nitro percentages does
not cause the engine to wear out faster. 33% Top Fuel contains the
same quality lubrication package as 10 and 20% Top Fuel. Some
non-Traxxas high-percentage nitro racing fuels do sacrifice some
lubrication in attempts to increase performance. We urge you to
not take chances with your engine investment and use Top Fuel for
consistent performance and long engine life.
What about Other Fuels?
Can other brands of fuel be used besides Top Fuel? There are other
fuels that can provide satisfactory performance; however there could
be long-term costs in the form of decreased engine performance, loss
of tuning ease, and shorter engine life. Only use fuels that contain both
castor and synthetic oil.
Everyone has an opinion or a claim to make about fuel. The
engineering team at Traxxas has spent years developing TRX Racing
Engines. No one knows more about the specific fuel requirements of
Traxxas engines, than Traxxas engineers. We strongly urge you not to
take chances with your engine investment and use the Traxxas fuel
made for the TRX 3.3 Racing Engine.
Handling the Fuel
Follow all directions and warnings on the fuel can.
Keep the fuel tightly capped at all times. Some components in the fuel
can evaporate very quickly and upset the balance of the fuel.
Do not store unused fuel in the fuel dispenser. Immediately return
fresh unused fuel back into the fuel can.
Do not mix old and new fuel. Never mix different fuel brands together.
Store the fuel in a cool dry location, away from any source of heat,
ignition, or combustion.
Read and follow the safety precautions on page 4 in this manual.
The TRX 3.3 Racing Engine
Filling the Fuel Tank
Use a fuel dispensing bottle (Traxxas Top Fueler, part
#5001) to put fuel into Slayer’s fuel tank. To fill the
fuel bottle, squeeze the air out, insert the dispenser
tip into the fuel can, and release
your grip on the bottle. As the bottle
expands, fuel will be drawn into it.
To fill your model, pull up on the
fuel cap handle, insert the tip of the
fuel bottle, and squeeze to dispense
the fuel.
The TRX 3.3 Racing Engine in this
model is equipped with a specially
designed two-stage air filter to deliver maximum filtering efficiency and
performance while protecting your engine from dust and dirt during
extended operating conditions. Use only the supplied filter. You will
not improve engine performance by switching to an aftermarket
filter, and you may risk engine damage due to poor filtration.
The two-stage TRX Racing Filter consists of the following components:
1. A rubber filter Base
2. A 3-piece plastic housing
3. A “pre-filter” element
4. A “primary” filter element
You must clean the outer pre-filter after every hour of run time,
even if the filter looks clean. The primary filter element inside must
be cleaned after 3-4 hours of run time. These intervals include
the break-in time. Clean your air filter after break-in. Dust (which
is often too fine to see) and dirt constantly move through the filter
anytime the engine is running. Even if you can’t see dirt on the filter,
it is present inside the foam after any amount of run time. If you
exceed the recommended cleaning intervals, your engine will be
damaged. Engine damage or wear due to dirt ingestion is easy to
detect, and one of the top causes of premature engine failure.
Pre-Filter Cleaning Instructions (every hour of run time)
1. Remove the clip from the air filter and remove from the metal
hanger. Remove the air filter assembly from the carburetor bore
by pulling the entire filter assembly firmly to the side to release it.
Do not pull straight up.
2. Remove the pre-filter element.
Pull to the side to remove assembly
3. Clean the pre-filter element by
thoroughly washing the foam
element in hot soapy water
(dishwashing detergent works
well). Repeat twice.
4. Thoroughly dry the pre-filter
element with a clean towel.
5. Oil the foam element with air
filter oil. Use Traxxas filter oil (part# 5263) or a high-quality, specialpurpose foam filter oil like what is used for off-road motorcycle
and ATV engines. This type of filter oil is available at motorcycle
pro-shops. Apply a total of 24 drops of Traxxas air filter oil, evenly
distributed between the top, bottom and sides of the filter element.
Squeeze the filter element repeatedly to help spread the oil
throughout. The filter element should be evenly colored by the oil.
Even color indicates that the oil is spread evenly. Do not squeeze
out excess oil. Note: Do not use the air filter oil for anything other
than the air filter. It is not meant to be a lubricant.
6. Reassemble the filter and install it on the engine. Make sure the
rubber filter neck fits securely on the carb with no gaps or air leaks.
Primary Filter Cleaning Instructions (every 3 - 4 hours of run time)
1. Remove the clip from the air
Pull to the side to remove assembly
filter and remove from the
metal hanger. Remove the
air filter assembly from the
carburetor bore by pulling
the entire filter assembly
firmly to the side to release it.
Do not pull straight up.
2. Remove the pre-filter element.
3. Remove the 3x6mm screw in the end of the filter housing.
Remove the front housing and the primary filter element.
4. Clean the filter parts by thoroughly washing in hot soapy water
(dishwashing detergent works well). Repeat twice for the foam
filter elements.
5. Thoroughly dry the foam pre-filter and primary filter elements
with a clean towel. Dry the remaining filter parts.
6. Oil the foam pre-filter with 24 drops of air filter oil, and the
primary filter element with 30 drops of air filter oil.
7. Reassemble the filter and install it on the engine. Make sure the
rubber filter neck fits securely on the carb with no gaps or air leaks.
Slayer • 21
The TRX 3.3 Racing Engine
The Carburetor
See page 29 for more
information on how air
density affects engine tuning.
A “turn” refers to
tightening (“turning in”) or
loosening (“turning out”)
mixture needles. A “full
turn” refers to turning the
needle 360°, so a “1/2 turn”
would be 180°, a “1/4 turn”
would be 90°, and so on.
Full Turn
Understanding the Carburetor adjustments
The carburetor performs several functions. It controls the engine’s
speed by restricting the intake of air and fuel into the engine. It
atomizes the fuel (suspends the fuel droplets in the air) and also
controls the air/fuel ratio of the mixture entering the engine (how
much air for a given amount of fuel).
The Fuel Mixture Needles
1/2 Turn
To help provide a better understanding of engine tuning and why
it’s necessary, the following is a brief explanation of the air/fuel
combustion process that takes place inside the engine.
22 • Slayer
(Warm Air) Less Dense
1/8 Turn
To make the high speed
needle easier to see
while the body is on, we
recommend marking the
surface white or silver paint.
A paint pen works very well
for this. You can also use
white correction fluid.
Cold Air (More Dense)
1/4 Turn
3/4 Turn
correct air/fuel ratio. Warmer air is less dense (fewer air molecules)
and therefore needs less fuel to maintain the correct air/fuel ratio. The
tuning needles are there to adjust how much fuel is made available for
the carburetor to mix with the available air (atomization).
In order to create the cylinder pressure that results in power, the
engine burns the air/fuel mixture. Both air and fuel, in correct
amounts, are needed for proper combustion. It is the carburetor’s
job to mix the air and fuel together (atomize the fuel), in the correct
proportion for the best possible combustion. This is the ideal air/fuel
ratio. The ideal air/fuel ratio required for the engine remains roughly
constant. Due to variations in atmospheric conditions (temperature,
humidity, altitude etc.) fuel flow adjustment valves (called fuel mixture
needles) are required to meter the fuel and maintain the ideal air/
fuel ratio in these ever-changing conditions. For example, colder
air is more dense (more air molecules) for a given volume of air and
therefore requires more fuel (more fuel molecules) to maintain the
The amount of fuel metered and atomized by the carburetor is
controlled by the two mixture needles, the high-speed needle and
the low-speed needle. The low-speed needle is used to meter the fuel
used by the engine at idle and low rpm (part-throttle) engine speed.
The high-speed needle is used to meter the fuel when the throttle is
open from part throttle to wide-open throttle (WOT). Two needles on
the TRX 3.3 Racing Engine provide precise control of the air/fuel ratio
across the engine’s entire rpm range.
The maximum possible fuel flow is always controlled by the highspeed needle. It works like the main water valve on a garden hose.
Turn it clockwise to close the valve, counter-clockwise to open it.
When the throttle is at idle or partially open, the low-speed needle
meters the fuel flow at the outlet (needle seat) where the fuel enters
the carburetor venturi. This second valve acts like the spray nozzle
at the end of the garden hose in our example. When you accelerate
from idle, the throttle opens and the low-speed needle is pulled away
from the needle seat. This allows more fuel to flow with the increased
air flow. As the throttle is increased, the low-speed needle is pulled
completely away from the needle seat leaving it fully open. At that
The TRX 3.3 Racing Engine
Water Valve
(Controls Overall Flow)
Slightly lean fuel mixtures deliver stronger, more efficient
combustion and more power, but with less lubrication.
Slightly rich fuel mixtures deliver cooler running and more
lubrication but with slightly­­­­less power.
High Speed Needle
Tuning the engine means finding the perfect balance between the
two; excellent power to meet your needs while maintaining good
lubrication for long engine life. The optimal fuel mixture setting
is rich to provide a safety margin against having a lean condition if
some variable changes (such as the temperature from one day to
the next).
Water Nozzle
(Controls Fine Flow)
Low Speed Needle
point, fuel metering is entirely controlled by the high-speed needle.
Again, using our water hose example, when the spray nozzle at the
end of our garden hose is fully open, then the main water valve can
be used to adjust how fast the water flows.
The engine’s performance is directly linked to the fuel mixture.
Richening the fuel mixture increases the amount of fuel in the
air/fuel mixture ratio and leaning the fuel mixture decreases the
amount of fuel in the air/fuel mixture ratio.
General fuel mixture settings are measured by the number of turns
the needles are turned out from fully closed. The fuel mixture settings
have been pre-set from the factory to typical break-in settings. Do
not readjust your carburetor from the factory settings until after the
engine is started and running, and you have been able to observe the
engine running to assess what minor adjustments may be required
to compensate for fuel, temperature, and altitude. Adjustments are
usually made in 1/8 or 1/16-turn increments. If the engine sticks at
TDC, see page 39 for instructions on freeing the engine.
The Idle Speed Adjustment
The idle speed screw controls the closed position of the throttle slide.
When the throttle servo is in its neutral position, the throttle slide
should be stopped against the idle adjustment screw. Always use
the idle speed adjusting screw to control engine idle. Do not use the
throttle trim on the transmitter to adjust idle speed. The idle speed
should be set as low as possible and still maintain reliable running.
See Tuning Your TRX 3.3
Racing Engine on page 28
for complete information on
adjusting the air/fuel mixture
and idle speed.
Factory Needle Settings
If your factory preset
carburetor adjustments have
been tampered with, use the
following settings:
• Set the high-speed needle to
4 turns out from closed.
• Set the low-speed needle so
the screw head (red in Fig. A)
is flush (even) with the end
of the slide (yellow in Fig. A).
Fig. A
Low Speed
Needle Adjustment
Always use the factory
settings for initial starting.
Only use these settings when
the factory settings have
been lost.
Higher nitro requires a richer
fuel mixture. When running
33% fuel, richen your high
speed needle 3/4 turn if
previously running 20% nitro
and then re-tune the engine
for maximum performance.
Slayer • 23
The TRX 3.3 Racing Engine
Inexpensive overnight wall
chargers may also be used
24 • Slayer
Installing the EZ-Start Battery
The EZ-Start system requires a fully charged 7.2-volt rechargeable
NiCad or NiMH battery pack (not included). Use a charger (not
included) designed for 7.2-volt battery packs. Charge the battery
according to the charger manufacturer’s directions.
1. Press the tab in the end of the battery
compartment door to open (A).
2. Plug a fully charged 7.2-volt
battery pack into the
connector inside (B).
3. Twist the battery two or
three times to twirl the
battery plug wires. This
helps hold the wire and
battery in place when the
battery is installed in the
compartment (C).
4. Install the battery into the
compartment and press the
wires securely into place.
5. Snap the battery compartment door back on and lock the
end tab (D).
If the Glow Plug LED fails to
light, the glow plug may be
bad, or the glow plug wire may
be damaged or disconnected.
Each of the two status indicator LEDs on
the hand-held control unit, the Motor LED
and the Glow Plug LED, should light green
while starting. If either LED fails to light
while starting, there is a fault indicated
with that function.
Using the EZ-Start
Your EZ-Start controller plugs into a 4-prong receptacle in the center of the
bed on your Slayer. When the red button on the controller is pressed, the
EZ-Start motor begins to spin the engine and power from the control unit
heats the glow plug. Assuming all settings and preparations are correct,
the engine should start almost immediately.
Power for the EZ-Start system comes from a 7.2-volt rechargeable
battery pack installed in the hand-held control unit (battery
sold separately).
The engine glow plug is heated automatically by the EZ‑Start
system, eliminating the need to keep up with a separate glow plug
The voltage to the glow plug is kept constant, regardless of the
load placed on the starter by the starter motor.
The “Glow Plug” LED (light emitting diode) on the control unit
indicates the condition of the glow plug.
The “Motor” LED indicates the status of the EZ-Start electric
starter motor.
The cush drive mechanism in the drive unit prevents damage to the
gears caused by engine kickback.
Smart Start™ protection circuitry prevents damage to the motor by
cutting power if the load on the motor or other electronics exceeds
safe limits.
If you’re using a 15-minute
timed charger, always
fully discharge the battery
pack before each charge.
Some high mAh battery
packs (1500 mAh or
higher) require more than
the standard 15 minutes
of charge time. If the
battery pack is cold after
15 minutes of charging,
add another 5 minutes
of charge time. Closely
monitor the battery
pack and stop charging
it when it begins to feel
warm to the touch. Never
leave a battery charging
unattended. Always follow
charger manufacturer’s
The Traxxas EZ-Start brings the convenience of push-button electric
engine starting to your Slayer. The EZ-Start consists of a hand-held
control unit and an on-board motorized starter.
Use the Right Charger
The most convenient type
of charger is an AC peakdetecting charger that
plugs directly into an AC
wall outlet, such as the TRX
Power Charger (see page 11
for more info). It contains
special peak-detection
circuitry that automatically
shuts the charger off when
the battery is fully charged.
If the Motor LED fails to
light and the starter fails to
operate, then the EZ-Start is
in protection mode.
Protection Mode
The EZ-Start uses Smart Start™ technology to monitor the condition
of the system and detect failures. The controller monitors the load
being placed on the EZ-Start motor. If the load becomes excessive,
the system shuts off power to the motor to prevent costly damage
to the motor and the controller. This may occur, for example, if the
engine floods with fuel during starting. The starter spins at first but
when excessive fuel in the combustion chamber begins to lock up the
engine, the starter motor slows under the heavier load. This causes
the protection circuit to shut off the power to the motor. Allow at least
3 minutes for the starter motor to cool and the circuit to automatically
reset before continuing. Use the time to find and eliminate the
condition that caused the excessive load on the starter motor.
The TRX 3.3 Racing Engine
Use a Strong Starter Battery
A weak starter battery, or one that has not been fully charged, may
not deliver enough power to crank the engine over at the appropriate
rpm to keep the piston from sticking at top dead center (TDC). A new
engine will typically have a tight fit between the piston and the top of
the sleeve. This is a tapered fit, and a tight piston sleeve fit on initial
startup is desirable for those who want the best-performing engine.
Make sure you are using a good quality battery pack that is fully
charged (new batteries usually require several charge cycles to reach
peak voltage and full capacity). This is especially important with a new
engine that needs to be broken in. If the engine sticks at TDC, see
page 39 for instructions on freeing the engine.
When the EZ-Start controller
is in protection mode, wait
at least three minutes before
attempting to start the
engine, to give the starter
motor time to cool.
It’s normal for your EZ-Start
controller to become warm
after repeated use.
Shutting Off The Engine
Turning off the switch for the radio will not
shut off the engine. To shut off the engine,
use the shut-off clamp on the fuel line.
Squeeze the clamp closed to shut off the fuel
supply to the engine. Don’t forget to release it
when you restart the engine.
Avoid shutting off the engine by placing your finger over the exhaust
outlet, especially if you are through driving for the day. This will
leave more unburned fuel in the engine that could lead to harmful
corrosion. Always be careful not to touch the exhaust pipe after
running, it can become very hot.
Slayer • 25
The TRX 3.3 Racing Engine
See Important Points to
Remember on page 4 for other
Never run your Slayer indoors.
Since the TRX 3.3 Racing
Engine exhaust fumes are
harmful, always run your
model outdoors, in a wellventilated area.
Your TRX 3.3 Racing Engine
doesn’t usually require priming.
If you do need to prime your
engine, watch the fuel line
carefully to avoid flooding
your engine. See page 39 for
information on clearing a
flooded engine.
Factory Needle Settings:
Your carburetor is preset at
the factory to give the correct
air-to-fuel ratio and idle speed
for engine break-in. Do not
adjust the carburetor unless
you observe a poor running
condition that requires
correction (see page 23 for
stock settings).
Higher nitro requires a richer
fuel mixture. When running
33% fuel, richen your high
speed needle 3/4 turn if
previously running 20% nitro
and then re-tune the engine
for maximum performance. See
page 20 for more information.
26 • Slayer
The TRX 3.3 Racing Engine uses a ringless, aluminum-brass-chrome
(ABC) piston/sleeve construction. This type of engine design relies on
a very precise running fit between the piston and sleeve for cylinder
sealing. Engine break-in is necessary to allow the piston and sleeve
to develop an extremely precise fit and optimum cylinder sealing.
Therefore, proper engine break-in is critical to achieving the fastest,
most reliable engine performance.
Allow yourself about 1 to 11/ hours to complete the break-in procedure.
The engine break-in period will take 5 tanks of fuel in a Slayer. The break-in
time is not the time to impress your friends with your new Slayer. You must
wait until the engine is fully broken in before attempting sustained high
speed running. Patience and careful attention during break-in will reward
you with the best-performing TRX 3.3 Racing Engine possible.
During break-in, your engine may appear to malfunction with
symptoms like stalling, inconsistent performance, and fouled glow
plugs. These are simply the normal “break-in pains” engines sometimes
go through. They will disappear once your engine is fully broken in.
Many owners report not experiencing any of these symptoms with TRX
Racing Engines. We recommend to go ahead and replace the glow
plug with a new one after the engine break in procedure.
Engine Break-in Procedure
The focus during break-in is to vary and limit the engine speed. This will
be accomplished by accelerating and stopping at different rates for the
first 5 tanks of fuel. As the engine begins to break-in, the duration and
intensity of the acceleration will gradually increase. Sustained highspeed running is not permitted until the 6th tank of fuel. Perform the
initial break-in on a large, flat, paved surface. Slayer is very fast and by
tanks 4 and 5 you will need plenty of room for the truck to run in.
Apply all throttle and braking actions gently. Abrupt acceleration or
braking could cause the engine to stall unnecessarily.
Special break-in fuels are not recommended. Use the same fuel you
plan to use everyday.
If possible, avoid breaking-in the engine on extremely hot or cold
days (see page 28).
Pay careful attention to the fuel level. Do not allow the fuel tank to
run completely empty. An extremely low fuel level causes the mixture
to run too lean. This could result in a burned glow plug or extremely
high engine temperatures.
Do not attempt to break in the TRX 3.3 Racing Engine by idling it
on a stand. This will produce poor results.
Keep extra Traxxas glow plugs handy. The break-in process can cause
deposits to form on the plug leading to plug failure.
Change or clean your air filter after break-in.
Follow the instructions exactly for each of the first 5 tanks of fuel.
Starting Your TRX 3.3 Racing Engine for the First Time
Before you start your TRX 3.3 Racing Engine for the first time, make sure
you have read all instructions and precautions in this manual. Pay close
attention to the tank-by-tank break-in instructions in the next section,
and make sure you have read and understood them before you run
your engine.
Your engine must be at room temperature (70°F or 21° C) or above the
first time you start it. If it’s cooler than room temperature outside, remove
all fuel and keep your Slayer indoors until you’re ready to start it and then
take it outside. If it’s colder than 45 degrees, special considerations should
be made. See cold weather break-in on page 28. We do not recommend
running the model in temperatures below 35 degrees.
1. Turn on the radio system (see page 14).
2. Make sure the throttle trigger on the
transmitter is in the idle (neutral) position.
3. Connect the EZ-Start controller according to
the instructions on page 24.
4. Press the starter button in short two second
bursts and watch for fuel moving through
the fuel line up to the carburetor. Watch
closely! The fuel moves very fast. If the fuel
doesn’t move through the line within 5 seconds, prime the engine
by briefly (one or two seconds) covering the exhaust outlet with your
finger until the fuel is just visible in the carburetor fuel line. Watch
carefully! If the engine is primed too long, it will flood with fuel and
stop turning.
5. Once fuel reaches the carburetor, the engine should
quickly start and idle.
6. Disconnect the EZ-Start controller from the model.
7. Proceed with the engine break-in.
8. Do not rev your engine with no load (wheels off the ground).
If your engine doesn’t start, go online to www.traxxas.com/support.
If your factory fuel mixture settings have been altered, refer to page
23. If you still have problems, contact Traxxas Customer Support at
1-888-TRAXXAS or [email protected]
The TRX 3.3 Racing Engine
Tank 1
1. Drive the model with the body off.
2. Driving procedure: Gently pull the throttle trigger to 1/4 throttle
over a 2-second count. Then gently apply the brake to stop.
Count the two seconds out while accelerating: one thousand one,
one thousand two, and then stop. Operate the throttle trigger as
smoothly as you can. Repeat this starting and stopping procedure
until the first tank of fuel is nearly empty.
3. Look for thick blue smoke exiting the exhaust outlet. If there is
no smoke, richen the high-speed needle 1/4 turn, by turning the
needle counterclockwise.
4. When the fuel tank is nearly empty, shut off the engine by pinching
the fuel line connected to the carburetor (use the installed clamp).
5. Let the engine cool for 15 minutes.
Note: If at any point the engine cuts out or stalls during gentle
acceleration, richen the high-speed needle 1/4 turn by turning the
needle counterclockwise.
Tank 2
1. From tank 2 forward, Slayer should be driven with the body on.
2. Driving procedure: Gently pull the throttle trigger to 1/2 throttle
over a 2-second count. Then gently apply the brake to stop. Count
the two seconds out while accelerating: one thousand one, one
thousand two, and then stop. Repeat this starting and stopping
procedure until the second tank of fuel is nearly empty.
3. When the fuel tank is nearly empty, shut off the engine and let it cool
for 15 minutes.
Tank 3
1. Driving procedure: Gently pull the throttle trigger to 1/2 throttle
over a 3-second count. Then gently apply the brake to stop. Count
the three seconds out while accelerating: one thousand one, one
thousand two, one thousand three, and then stop. Repeat this
starting and stopping procedure until the third tank of fuel is
nearly empty.
2. As the engine loosens, the idle speed may increase and cause
the model to try to creep forward when stopped. Reduce the
idle speed by turning the idle adjustment (see page 17) on the
carburetor counterclockwise.
3. When the fuel tank is nearly empty, shut off the engine and refuel.
From here on, you do not need to let the engine cool between tanks.
Tank 4
1. Driving procedure: Gently pull the throttle trigger to full throttle
over a 3-second count. Then gently apply the brake to stop. Count
the three seconds out while accelerating: one thousand one, one
thousand two, one thousand three, and then stop. Repeat this
starting and stopping procedure until the fourth tank of fuel is
nearly empty.
2. Apply the throttle gradually! Your finger should not reach full throttle
until the end of the three-second count. Slayer may try to shift into
second gear. If it does, reduce the throttle input. Do not let Slayer
shift out of first gear.
3. Keep your driving smooth and consistent.
4. When the fuel tank is nearly empty, shut off the engine and refuel.
Tank 5
1. Driving procedure: Gently pull the throttle trigger to full throttle
over a 3-second count, hold for 2 more seconds, and then
gently apply the brake to stop. Count the five seconds out while
accelerating. Repeat this starting and stopping procedure until the
fifth tank of fuel is nearly empty.
2. The model should now be shifting into second gear. If it is not, try
turning the high-speed needle clockwise 1/8 turn to lean the fuel
mixture slightly and test for shifting.
3. When the fuel tank is nearly empty, shut off the engine and refuel.
Tank 6
STOP! Clean your air filter before you proceed. Refer to the instructions
on page 21. During the sixth tank of fuel, the engine can be tuned for
general performance use. Proceed to the next section in this manual.
2 seconds
15 minutes
High Altitude Operation:
If you live in a high
altitude region (5000 or more
feet above sea level), the
lower air density may require
you to lean your high-speed
fuel mixture slightly from the
factory break in settings. Try
this if you are experiencing
difficult starting or extremely
sluggish engine performance
at high altitude.
As you gain experience in
the hobby, you may discover
that many people have
differing opinions on what
is the proper procedure to
break-in a model engine.
Only use the Traxxas break-in
procedure. Other break-in
procedures could result in a
weak, damaged, or otherwise
poor performing engine.
The procedure outlined
here was extensively tested
and proven to yield better
performing engines than
other “common” break-in
methods. Even if you have
years of experience using
model engines, please do not
ignore this caution!
Apply throttle gradually.
2 seconds
15 minutes
Apply throttle gradually.
3 seconds
Reduce idle speed if necessary.
3 seconds
Do not allow shifting to high gear.
5 seconds
Accelerate over 3 second count, hold for 2 seconds.
Slayer • 27
The TRX 3.3 Racing Engine
When tuning for
performance, watch closely
to notice when there is no
longer any increase in speed
or power when the
high-speed mixture is lean.
If you lean the high-speed
mixture to the point that the
engine cuts-out, hesitates,
or stalls, you are well into
the danger zone and engine
damage is likely. Richen the
high-speed needle 1/4 turn
and retune.
For your convenience, the
low-speed needle has a
positive stop that prevents
it from being over tightened
and damaging the needle
and seat. This also provides
an easy way to gauge how
many turns out from closed
the low-speed needle
adjustment is set to.
28 • Slayer
Winter Break-in Tips
During the break-in process, the piston and sleeve wear into each other
to form a precise fit. The engine needs to heat up to a temperature
around 200 to 215 degrees to allow the piston and sleeve to achieve
this fit properly. A precise fit between these two components is critical
for proper compression, and optimum performance. If the engine runs
too cold during break-in, the piston and sleeve will not expand to their
appropriate sizes for break-in, and this can lead to premature wear of
these components. This wear may not become apparent until after
winter has past, and the engine is operated under warmer running
Warm the engine to approximately room temperature by removing
all fuel and storing the vehicle inside at room temperature until just
before starting the engine. An extremely cold engine can become
difficult to start.
After the engine is running, it is important to keep the temperature
of the engine up around 200 to 215 degrees during break-in. In
weather below 45 degrees, the TRX 3.3 Racing Engine will tend to
run at lower temperatures between 160 to 180 degrees (when tuned
at proper break-in mixture settings). This is too cool for break-in. Do
not lean the fuel mixture to increase engine temperature! This
will also decrease lubrication and cause your piston/sleeve to wear
Wrap the cooling head with a paper towel,
clean rag or sock to help keep the engine
running around the recommended 200
to 215 break-in temp. If too much heat
is contained, the engine can actually run
too hot. Make sure that you monitor the
engine’s temp closely for the first couple
of tanks until you get the right amount of cover for the cooling head.
This will, of course, depend on your current weather conditions.
Adjusting the cover up and down, exposing more or fewer cooling
fins, is a convenient way to regulate engine temps.
For owners that do not have access to a temperature probe, a drop of
water on the cooling head (around the glow plug area) should slowly
sizzle for approximately 6 to 8 seconds around 200 to 210 degrees. If
the water sizzles for only a few seconds, then it is likely that it is over
220 degrees, and needs to cool down. If the water takes a long time
or does not evaporate at all, then the engine is too cool.
We do not recommend that you operate your engine below 35
degrees Fahrenheit. If you insist on running your vehicle below 35
degrees, be aware that nitro engines may be very difficult to start
and tune at extremely cold temperatures. Also, at temperatures
below freezing, nitro fuel can actually begin to gel up, and this can be
harmful to the engine.
Follow the remaining break-in procedures as outlined in this Owners
Manual. This, along with the steps listed above, will ensure a good breakin for your new nitro engine, and provide many hours of enjoyment.
The engine’s performance
depends on the fuel
mixture. Turn the mixture
needles clockwise to
lean the fuel mixture and
counterclockwise to richen
it. Leaning the fuel mixture
will increase engine
power up to the engine’s
mechanical limits. Never
run the engine too lean
(not enough fuel flow).
Never lean the engine
until it begins to cutout or stall. Leaning the
engine beyond the safe
allowable limits will result
in poor performance and
almost certain engine
damage. Indications of an overly lean mixture include:
Cutting out or sudden loss of power during acceleration.
Overheating (temperature beyond 270° F at the glow plug).
Little or no blue smoke coming from the exhaust.
If any of these conditions are present, stop immediately and richen
the high speed mixture 1/4 turn. The engine will probably be slightly
rich at that setting and you can then retune for performance. Always
tune for performance by starting rich and moving leaner toward the
ideal setting. Never try to tune from the lean side. There should always
be a light stream of blue smoke coming from the exhaust.
The TRX 3.3 Racing Engine
Before you begin tuning, the engine should be warmed up to its normal
operating temperature and running slightly rich. All final tuning adjustments
must be made to the engine at its normal operating temperature. You can
tell the engine is running rich by noting any of the following:
Sluggish acceleration with blue smoke coming from the exhaust.
Slayer may not shift into second gear.
There is unburned fuel spraying from the exhaust tip.
Leaning the high-speed fuel mixture increases performance.
High-Speed Fuel Mixture Adjustment
With the engine warm and running at a rich setting, gradually lean the
high-speed fuel mixture in 1/16 turn increments. Make several highspeed passes after each adjustment to clear out the engine and note any
change in performance. The TRX 3.3 is extremely powerful. Remember
to apply the throttle gradually to prevent wheelies or loss of control.
Continue this procedure until there is no longer any performance
improvement. If any one of the following conditions occurs, the fuel
mixture is already past the maximum safe lean setting:
1. There is no longer any performance improvement.
2. The engine begins to cut out at high speed (Danger!).
3. There is a sudden loss of power during acceleration (Danger!).
4. The engine begins to overheat. Symptoms of overheating include:
Steam or smoke coming from the engine (not exhaust).
Hesitation or stalling during acceleration.
Popping or clattering sound when decelerating (detonation).
Fluctuating idle speed.
Temperature measurement above 270° F at the glow plug
(A temperature reading above 270° alone does not necessarily
indicate overheating. Look for other symptoms of overheating
combined with temperature for a more accurate warning).
Richen the fuel mixture to the optimum setting by richening the
high-speed needle at least 1/8 turn counterclockwise and retest. This
setting will extend engine component life.
Low-Speed Fuel Mixture Adjustment
The low-speed mixture is always set after the high-speed needle is
correctly adjusted. The low-speed mixture is set using the pinch test.
2. Bring the vehicle in and pinch closed the fuel line going into the
carburetor (use the engine shut-off clamp). The engine should run for
2-3 seconds, speed up, and then shut off.
3. If the engine runs longer than 3 seconds, then lean the low-speed
needle 1/16 turn, make several more high-speed runs, and retest.
4. If the engine shuts off immediately without speeding up, then richen
the low-speed needle 1/8 turn, make several more high-speed runs,
and retest.
When the low-speed needle is set correctly, the engine’s throttle response
should be very quick, even to the point of making it difficult to keep
Slayer from doing a wheelie when you accelerate!
Fuel Mixture Adjustment Chart
then the air
density is...
adjust (correct) the
fuel mixture to be...
more dense
Slightly richer
less dense
Slightly leaner
Less dense
More dense
More dense
Less dense
More dense
Less dense
If the...
Nitro %
When adjusting the low
speed fuel mixture, it is very
important to make several
high-speed runs with Slayer
between adjustments to
clear out any excess fuel.
Perform the pinch test
immediately after. If the
engine is allowed to idle
for a long period of time, it
could “load up” with fuel
and give you an inaccurate
measurement from your
pinch test.
Higher nitro requires a richer
fuel mixture. When running
33% fuel, richen your high
speed needle 3/4 turn if
previously running 20%
nitro and then re-tune the
engine for maximum
performance. See page 20
for more information
1. Once the engine is warm, do several high-speed runs to confirm
that the high-speed needle is set correctly.
Slayer • 29
The TRX 3.3 Racing Engine
Idle Speed Adjustment
Once the high and low-speed mixtures have been set, reduce the idle
speed to the minimum reliable idle speed. Remember, this adjustment
should be made while the engine is running at normal operating
1.Turn the throttle trim on the transmitter so the brakes are
applied (note its original position). This ensures that the throttle
slide is resting against the idle adjustment screw.
2.Turn the screw counterclockwise to reduce the idle speed, or clockwise
to increase it. The idle speed should be set as low as possible while still
maintaining reliable running characteristics.
3.Reset the throttle trim on the transmitter to its original position.
Fine-Tuning the Carburetor
After fine-tuning your TRX 3.3 Racing Engine at the end of the breakin procedure, no major adjustments to the fuel mixture are usually
necessary. Make note of the temperature, humidity, and barometric
pressure at the time you finished fine tuning your carburetor. Current
weather conditions can be found online from national websites, local TV
news websites, and television. This information will be considered your
baseline setting.
You may need to adjust your carburetor needles to compensate for
changes in temperature and barometric pressure (air density) from day to
day. Generally, you’ll need to richen the fuel mixture when the weather is
colder than your baseline temperature and the air density is higher. Lean
the fuel mixture when weather is warmer than your baseline temperature
and the air density is lower. The chart below provides general guidelines
on how weather conditions affect air density when they move higher or
lower than your baseline setting (see page 22 for detailed info on how air
density affects mixture settings).
Tuning the Engine by Temperature
The following procedures require an
optional infrared temperature probe or
on-board temperature gauge (Traxxas
on-board digital temperature gauge, part
#4091). Engine temperature can be used
as an effective tuning aid when you understand the relationship between
engine temperature and ambient temperature. The engine operating
temperature, when tuned for maximum performance, will vary according
to atmospheric conditions, engine load, gauge accuracy, and many other
factors. The atmospheric condition that has the most influence on engine
30 • Slayer
temperature is air temperature. Expect the engine temperature to vary
almost in direct proportion to air temperature. Assuming you tuned
the engine for the same maximum performance each day, the engine
will run about twenty degrees hotter when it’s ninety degrees outside
than it would in seventy-degree weather. For this reason, we cannot
give you a definitive temperature range that indicates the best possible
engine tuning.
There is NO optimal temperature that can be used as a target to deliver
the best engine tuning. Do not rely on a temp gauge alone to tune
your engine. Tune the engine by paying very close attention to how
it responds to changes in fuel mixture (more smoke/less smoke, fast/
sluggish, reliable/stalling, smooth sound/ muffled sound, etc).
Once the engine is tuned, then observe the temperature.
The temperature gauge can aid you in tuning by giving you a relative
indication of how your adjustments are affecting the engine and to help
prevent you from reaching excessive engine temperatures. For example,
as you lean the fuel mixture, the engine performance will increase along
with the temperature. If you continue to lean the fuel mixture and the
temperature increases but the engine performance does not change,
then you have exceeded the maximum safe lean setting. Make note of the
engine temperature. Generally, try to keep your engine from exceeding
270°F when measured at the glow plug. If necessary, increase airflow
to the engine by cutting out the rear of the body, windshield, and front
valance. In some situations, the engine may perform very well with no
stalling, lagging, or hesitation at temperatures above 270°F, particularly in
very hot climates.
If richening the fuel mixture to bring the temperature down to 270°F
results in poor, sluggish performance (engine never cleans out) then return
the engine back to a satisfactory state of tune based on how it sounds and
performs (always with a visible stream of blue smoke coming from the
exhaust)­. If engine temperature is exceeding 270°F with proper cooling
and no signs of abnormal running, then avoid running the engine at its
maximum lean setting. Watch closely for any signs of overheating.
Richen the fuel mixture slightly to provide a safety margin of additional
cooling lubrication. Symptoms of overheating include:
Steam or smoke coming from the engine (not exhaust).
Hesitation or stalling during acceleration.
Popping or clattering sound when decelerating (detonation).
Fluctuating idle speed.
Driving Your Slayer
Your TRX 3.3 Racing Engine is broken in, the fuel mixture is balanced,
and the idle is set…now it’s time to have some fun! Before you go on,
here are some important precautions to keep in mind.
Don’t run your Slayer in water, mud, snow, or wet grass.
It’s tempting, but water and mud are easily drawn through the
air filter and will severely damage the engine. Small amounts of
moisture can cause electronics to fail and loss of control over
your Slayer.
The TRX 3.3 Racing Engine is extremely powerful. Remember to
apply the throttle gradually to prevent wheelies or loss of control.
Don’t hold Slayer off the ground and rev the engine excessively
with no load on the engine. This practice could result in internal
engine damage. Avoid over revving the engine when Slayer is
airborne after a jump.
Avoid excessive high-speed running for extended periods of time
or over long distances. This could cause the engine to build up
enough speed to exceed maximum safe RPM limits.
Don’t drive your Slayer with drive train damage of any kind.
The engine could be damaged due to overloads caused by
drivetrain friction, or over-revving caused by loose or missing parts.
Driving Tips
Slayer is very fast. Select a large area to drive with few
opportunities for collision until you become familiar with Slayer’s
speed and handling.
Do not apply brakes and turn the wheel at the same time. You
could tip the truck over.
When jumping, apply some throttle while Slayer is in the air to
keep the truck’s nose up and land level on all 4 wheels. Be careful
not to over-rev the engine or land at full throttle. Either could
seriously damage your Slayer. If the nose of the truck is too high,
then quickly tap the brake to level the truck in the air.
Drive over large obstacles (such as curbs and rocks) at an angle,
instead of head on. This will allow the suspension to articulate and
absorb the impact much easier.
Change or clean the pre-filter element in your air filter after each
hour of running. Change or clean the primary filter element every
3 - 4 hours of running. This is critical for the life of your engine.
Running time includes the engine break-in period.
Don’t tow anything with your Slayer. The engine is cooled
by airflow created by speed. Towing creates a high load on the
engine, and at the same time limits cooling of the engine due to
low vehicle speed.
If your Slayer gets stuck, stop driving immediately. Move the
vehicle and then continue driving.
Never turn off the radio system while the engine is running. The
truck could run out of control.
Slayer • 31
Basic Tuning Adjustments
This tuning and setup guide is separated into two sections- Basic
and Advanced. Slayer does not require any specialized knowledge or
understanding of its unique suspension and drive train to perform
typical, everyday setup and track tuning adjustments. Adjustment
procedures for alignment, spring rate, damping, steering, and ride
height are covered in the basic tuning section. Adjustments for the
gear ratio, two-speed shift point, slipper clutch, and brake are also
covered. In most cases, the basic information is all that is needed to
tune Slayer to perform well on a variety of surfaces.
Slayer was engineered to provide sophisticated additional tuning
options well beyond the basics that allow expert users to extract the
maximum performance from the truck. The advanced tuning section
(beginning on page 40) covers topics such as optional suspension
rockers, roll center adjustment, caster adjustment, bump steer tuning,
differential setup, and fine tuning the two-speed gear ratios. Make
sure you fully understand the basic adjustments before experimenting
with the advanced adjustments. Improper combinations of
adjustments can adversely affect the performance of the truck,
resulting in poor handling. If you don’t know why you are changing an
adjustment then you should leave it at its factory setting.
The front and rear
springs on Slayer have
different spring rates.
The rear springs are
about 12% stiffer than
the front springs. The
spring’s pre-load tension
can be adjusted by
turning the spring pre!XLE#ENTERLINEAT-AX#OMPRESSION
load adjuster. Adjusting
the pre-load changes the
suspension sag and ride
height. Suspension sag
basically defines how
much the suspension compresses when the truck is at rest. Adjust
the pre-load so that the suspension compresses about one third of its
full suspension travel (see illustration). If suspension sag is severe and
requires a large increase of the spring pre-load to compensate, then a
firmer spring should be used.
32 • Slayer
Use a stiffer spring to reduce sag, reduce body lean, control brake
dive, and provide a firmer, more responsive overall feel. If Slayer
is lightened significantly for racing applications, softer springs will
be necessary to allow the suspension to sag properly. Heavier
configurations will require stiffer springs. The suspension sag
and spring pre-load should be readjusted anytime the springs are
removed and/or replaced.
Optional springs available from Traxxas are listed below. Refer to your
parts list for a complete part number listing. Higher rate springs are
stiffer. Springs can be identified by dots of color on one end.
Spring Color Stripe Color
Double Pink
Double Blue
Double Green
Double Black
Double Purple
Spring Rate
0.7 N/mm (4.0 lb/in)
0.9 N/mm (5.1 lb/in)
1.0 N/mm (5.7 lb/in)
1.1 N/mm (6.3 lb/in)
1.2 N/mm (6.8 lb/in)
1.3 N/mm (7.4 lb/in)
1.4 N/mm (8.0 lb/in) (Standard Front)
1.6 N/mm (9.1 lb/in) (Standard Rear)
1.8 N/mm (10.3 lb/in)
2.0 N/mm (11.4 lb/in)
2.3 N/mm (13.1 lb/in)
2.6 N/mm (14.8 lb/in)
2.9 N/mm (16.6 lb/in)
3.2 N/mm (18.3 lb/in)
Ride Height Adjustment
The rocker arm suspension uses push rods on each suspension arm.
Changing the length and/or position of the push rod adjusts the
ride height without affecting or compromising other suspension
parameters. For example, you can raise the ride height of the rear
suspension without changing up/down travel distribution, changing
springs, or affecting your progressive rate. Increasing the rear ride
height will increase ground clearance for rough terrain. The rear ride
height of the model can be changed by mounting the push rod in
the inner hole in the lower rear suspension arm. From the factory,
the rear push rod comes installed in the outer hole of the lower rear
suspension arm’s push rod mount. If the push rod is mounted in the
inner hole, the ride height of the vehicle increases. The ride height
can be tuned by adjusting the sag of the suspension. If suspension
sag is severe and requires a large increase of the spring pre-load to
compensate, then a firmer spring should be used.
Basic Tuning Adjustments
Adjusting the Pivot Ball Caps
The pivot ball caps should be
adjusted so that the pivot balls
operate freely in the axle carriers
with no excess play. Use the
provided four-way suspension
multi-tool to tighten or loosen
the pivot ball cap.
Shock Oil
The 4 oil-filled aluminum shocks (dampers) effectively control the
suspension movement by preventing the wheels and tires from
continuing to “bounce” after rebounding from a bump. Changing the
oil in the shocks can vary the suspension damping effect. Changing the
oil to a higher viscosity oil will increase damping. Lowering the viscosity
of the oil will cause the suspension damping to be reduced. Damping
should be increased (with higher viscosity oil) if the model is bottoming
easily over jumps. Damping should be decreased (with thinner viscosity
oil) if the model is hopping over small bumps and feels unstable. The
viscosity of shock oil is affected by extremes in operating temperature;
an oil of certain viscosity will become less viscous at higher
temperatures and more viscous at lower temperatures. Operating in
regions with cold temperatures may require lower viscosity oil. From
the factory, the shocks are filled with SAE-40W silicone oil. Only use
100% silicone oil in the shock.
5. Slowly move the piston up and down (always keeping it submerged
in oil) to release the air bubbles. Let the shock sit for a few minutes
to allow any remaining air bubbles to surface.
6.Slowly thread the upper cap with the installed shock bladder onto
the shock body with the suspension multi tool. The excess oil will
bleed out of the small hole in the shock cap.
7. Tighten the shock cap until snug. Use the included steel shock
wrench to hold onto shock body while tightening.
Important: The shocks are
assembled at the factory
with a center-to-center
distance (between the rod
end balls) of 87mm. Any time
the shocks are removed and
disassembled, this distance
should be checked to ensure
proper operation of the
For shock piston tuning see Advanced Tuning Adjustments on page 42.
Replacing Shock Oil
The shocks have to be
removed from the vehicle and
disassembled to change the oil.
1. Remove the lower spring
retainer and shock spring.
2. Remove the upper shock cap
using the shock wrench and
the suspension multi tool
3. Empty the used shock oil from the shock body.
4.Fill the shock with new silicone shock oil up to the top of the
shock body.
Slayer • 33
Basic Tuning Adjustments
Alignment Settings
A camber gauge (available
at your local hobby shop)
can be a useful tool for
alignment setting.
All of the toe links are installed
on the truck so that the left
hand thread indicators point
to the same direction. This
makes it easier to remember
which way to turn the wrench
to increase or decrease toe link
length (the direction is same at
all four corners). Note that the
groove in the hex indicates the
side of the toe link with the
left-hand threads.
The alignment settings are critical for optimizing the performance
of Slayer. Adjust your alignment as carefully and precisely as you
possibly can.
Toe Adjustment
The wheels can be adjusted to
point straight ahead or have a toein or toe-out setting. To help you
remember, look down at your feet.
For toe-in, your feet point towards
each other. For toe-out, your feet
point away from each other.
The toe angle of the front wheels
can be adjusted by varying the
length of the toe links that connect
the steering linkage to the front
axle carriers. The toe angle of
the rear wheels can be adjusted
by varying the length of the
metal toe links that connect the
rear bulkheads to the rear axle
carriers. The front toe links and
rear toe links are equipped with
turnbuckles. The lengths of the toe
links can be adjusted by turning
them with the included turnbuckle wrench.
The suspension pivot balls located in the
axle carriers adjust the static camber. The
pivot balls are protected by blue dust plugs. To adjust your static
camber, insert the supplied 2.5 mm hex wrench through the slit in
the dust plug and engage the end of the pivot ball (compressing the
suspension until the arms are parallel to the ground will allow for easier
hex wrench engagement). The upper pivot ball is normally screwed all
the way in. Negative camber is achieved by screwing the pivot ball of
the lower control arm out. Note: When camber is changed, the toe
angle of the wheel has to be reset.
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For caster, roll center, and
optional rocker arm tuning see
Advanced Tuning Adjustments
on page 40.
Static Camber Adjustment
The wheels can be set to have either
positive or negative camber (see illustration
below). The camber angle changes as the
wheel moves up and down through its
range of travel. Static camber is the camber
angle at the wheel0when
the vehicle is set at
its normal, stationary ride height.
Static Camber Base Factory Settings
Front: 2-degree negative camber each side
Rear: 2-degree negative camber each side
Toe Base Factory Settings
Front: 0-degrees
Rear: 1-degree toe-in each side
Positive camber
Under certain conditions, toe-in can be increased to a maximum
of 3 degrees.
Negative camber
34 • Slayer
Basic Tuning Adjustments
Adjusting the Slipper Clutch
Your Slayer is equipped with
an adjustable Torque-Control™
slipper clutch. The slipper clutch is
integrated into the main spur gear
on the transmission. The slipper
clutch is adjusted by loosening
the spring-loaded locknut on the
slipper shaft. Use the supplied
8mm open-end metric wrench. To
tighten or loosen the slipper nut,
insert the 2.0mm hex wrench into the hole in the
end of the slipper shaft. This locks the shaft for adjustments.
Turn the adjustment nut clockwise to tighten (less slippage) and
counter-clockwise to loosen (more slippage). The slipper clutch has
two functions:
1. Limiting the engine’s torque output to the wheels to prevent
wheelspin on low traction surfaces and help to prevent damage
to the gears in the transmission during on-throttle landings.
2. Protecting the drivetrain from sudden impact or shock loads (such
as landing from a jump with the engine at full throttle).
From the factory the slipper clutch is set for minimal slippage, just
enough to protect the drivetrain from shock loads. On slippery, low
traction surfaces such as a hard-packed, dry racetrack you may benefit
from loosening the slipper adjustment nut to allow for more clutch
slippage. This will make the truck easier and more forgiving to drive
by helping to reduce the amount of wheel spin. Loosening the slipper
adjustment can also improve performance on extreme high traction
surfaces by preventing the front end from lifting off of the ground when
accelerating. Make slipper adjustments in small 1/8 turn increments.
The maximum tight setting for the slipper is just at the point where
there is little or no tire slippage on a high traction surface such as
carpet or a prepared racetrack. The slipper should not be tightened
to the point that clutch slippage is completely eliminated. Do not
overtighten the slipper nut or you could damage the slipper bearings,
pressure plates, or other components.
Adjusting the Two-Speed Transmission
Slayer comes equipped with an adjustable two-speed transmission.
When the shift point on the transmission is adjusted correctly, it will
maximize acceleration and improve drivability. Use a 2mm hex wrench
to adjust the shift point. To make the adjustment, the engine must be
off (not running).
1. Shift the transmission into forward
gear (shift button down).
2. Remove the rubber access plug from
the top of the transmission housing.
3. While looking through the opening,
rotate the spur gear to align the
cutout (notch) on the internal twospeed clutch drum with the opening.
4. Hold the spur gear and slowly roll the
truck forward until the hex on the
black adjustment set screw becomes
visible in the opening. Note: the truck
will only roll forward (not backwards)
when the spur gear is held stationary.
5. Insert the 2.0mm hex wrench
through the clutch drum and into
the adjustment screw.
6. Turn the adjustment screw 1/8 turn
counter clockwise to lower the shift
point (shifts sooner). Be careful not to
loosen the adjustment screw too much
or you may cause the screw and spring
to fall out (requiring major disassembly
and repair). Turn the adjustment screw
clockwise for later shifts.
7. Reinstall the rubber access plug to prevent dirt from entering the
transmission. Do not put oil or other lubricants into the transmission
through the two-speed adjustment access.
8. Check performance by running a test lap after each adjustment. On
a small race track with many tight turns, try setting the shift point
later so that the truck only shifts into second gear on the main
straightaway. This will prevent an unexpected shift in the middle of
a turn. On larger tracks it may be necessary to allow earlier shifts for
increased speed.
Slayer • 35
Basic Tuning Adjustments
For adjusting twospeed and gear ratios
see Advanced Tuning
Adjustments on page 43.
Adjusting the Spur Gear/Clutch Bell Gear Mesh
The ideal spur gear/clutch bell gear mesh
for Slayer is 0.1mm. To set the gear mesh,
place a strip of standard letter/A4 size
copy or printer paper (about 0.1mm thick)
between the mating teeth. Loosen the two
horizontal engine mount screws and slide
the engine mount up to push the clutch bell
gear against the spur gear so that the that
the paper is not too tight to pull out or too
loose that it will fall out. Tighten the two
horizontal engine mount screws securely.
When the paper is removed, you should feel
only the slightest amount of play between
the gears (almost none) and there should be
no binding or friction.
Changing the Spur Gear
1. Remove the four cap head screws that
secure the engine to the engine mount.
2. Remove the button head screw that
secures the pipe hanger to the rear
body mount.
3. Carefully remove the engine and exhaust
system from the spur gear area to allow enough
room to remove the spur gear.
4. Remove the three screws on the slipper clutch
assembly using a 2.5mm hex wrench. Slide the
spur gear off of the slipper shaft. If the spur gear
is too tight on the shaft, gently pry on the back
of the gear with a flat screw driver to loosen it.
Repeat the above steps in reverse order to install the new spur gear.
Slayer uses a digital servo and a single heavy-duty servo saver for
powerful, responsive steering.
Adjusting The Steering System
1. Remove the servo horn and steering link from the servo.
Disconnect the steering link from the servo saver.
36 • Slayer
2. Adjust the steering link to be 31.7mm - use “Steering Servo Horn Link
Length Template” below to set length).
3. Switch on the power to the receiver and the transmitter.
4. Adjust the steering trim on the transmitter to the neutral “0” position.
5. Connect one end of the steering link to the servo saver arm and the
other end to the servo horn
6. Position the steering servo saver arm
perpendicular to the centerline of
the vehicle.
7. While holding the steering servo saver
arm in the position mentioned in step
6, install the servo horn onto the servo
so the steering link is parallel with
the centerline of the vehicle. This will
automatically set the servo horn at the
7-degree offset shown in the illustration.
Steering Link Length Template
If you are using an aftermarket servo, it is important to use a servo horn
designed for Slayer. Optional steering servo horns are sold separately
for use with non-Traxxas servos.
Servo Saver Tuning
An optional stiffer spring is available for the servo saver when using
servos with metal gear sets (see parts list for details). Do not use this
spring with standard Traxxas high-torque servos.
Slayer is equipped with a disc brake that rides on the yoke of the
transmission’s front output shaft. The brake is preset at the factory
and should not require attention. As the brake material wears, future
adjustments may be necessary.
Basic Tuning Adjustments
Brake Shoulder Screw Adjustment
The two shoulder bolts that are
used to secure the brake pads to
the transmission housing may
need to be adjusted periodically
as the brake material wears down.
They should be tightened so a
0.50mm (.020”) gap exists between the disk and the brake pad (on the
transmission side). Adjust in one of the following ways:
1. Use a .50mm feeler gauge between the brake pad insert and brake disk.
2. Push the outer brake pad firmly against the inner pad with your
finger, sandwiching the brake disk between the brake calipers.
Tighten the brake shoulder bolts until they just barely touch the
brake pads. Do not over tighten these fasteners or you could damage
the brake calipers. Loosen each of the shoulder bolts by 1 turn.
Brake Linkage Adjustment
When correctly adjusted, the brake linkage
spring should barely touch the rod guide
when the servo is in neutral position
(closed throttle). This will ensure no brake
drag during operation of the vehicle. The
brake adjustment knob can be threaded
away from the spring for less braking
power if desired. Do not adjust knob to
apply pressure against the spring while
the servo is in the neutral position.
This will induce brake drag and cause
undesirable handling.
Less Brake
Front of Truck
The position of the z-bend from the
factory is in the middle position of the
servo horn. Changing this position will
affect the way the brake force is applied. The brake adjustment knob
will need to be readjusted if this position is changed.
Brake Pad Wear and Replacement
During normal use the brake pads should wear at a relatively slow rate.
However, if the brake pads wear down close to the metal pad holders,
they should be replaced. Any more wear than this could cause damage
to the brake parts and improper operation of the brake system.
Slayer • 37
Maintaining and Storing Your Slayer
If the engine is worn or
damaged enough to require
replacing the piston,
sleeve, or connecting rod,
consider exchanging your
old engine for a brand new
engine under the terms of
the Traxxas Lifetime Engine
Replacement Plan (ERP). It
could save you time and
effort. Details are in your
model’s documentation
The TRX 3.3 Racing Engine
is designed to be easy to
rebuild. Critical engine
components such as the
crankcase, crankshaft, and
engine bearings are made
to extremely high quality
standards and should under
normal circumstances
outlast multiple sets of
pistons, sleeves, connecting
rods, and wrist pins
(reciprocating assemblies).
It could be more economical
for you to continue to use
your good bearings and
crankshafts, and simply
replace the reciprocating
assembly as needed. Engine
assembly is not difficult and
replacing the reciprocating
assembly does not require
any special tools or skills.
Your Slayer requires timely maintenance in order to stay in top running
condition. Neglecting the maintenance could allow dirt, deposits,
and moisture to build up inside the engine leading to internal engine
failure. The following procedures should be taken very seriously.
After each hour of running:
Clean and re-oil the air filter. The instructions for this procedure are
on page 21. We cannot stress enough the value of cleaning your air
filter at the scheduled intervals. The cleanliness and condition of your
air filter directly influences the running life span of your engine. Do not
skip air filter maintenance!
Clean the outside of the engine of accumulated dirt, oil, and grime.
Accumulated grime will decrease the engine’s ability to cool itself.
To maintain optimum radio system performance, the RX Power Pack
(receiver battery) should be recharged after each hour of runtime.
Tighten the wheel nuts (especially on the left side). Use the 8mm end
of the included glow plug wrench.
After each running session:
Perform after-run maintenance on the engine. This clears the engine
of destructive moisture and other corrosive deposits. This is extremely
important for the life of the engine. Read on for after-run maintenance
Inspect the gears for wear, broken teeth, or debris lodged
between the teeth
Inspect the vehicle for obvious damage or wear. Look for:
1. Loose or missing screws
2. Cracked, bent, or damaged parts
3. Cut or loose wiring
4. Cut or kinked fuel lines
5. Signs of fuel leakage
Other periodic maintenance:
Connecting rod: The connecting rod should be replaced when the
piston and sleeve are replaced. Also replace the piston wrist pin and
G-clip whenever the connecting rod is replaced. As with other internal
engine components, connecting rod life depends engine’s usage and
the quality and frequency of the engine maintenance. Inspect the
connecting rod after 3-gallons of fuel have been used.
Slipper clutch pads (friction material): Under normal use, the friction
material in the slipper clutch should wear very slowly. If the thickness
38 • Slayer
of any one of the slipper clutch
pads is 1.8mm or less, the friction
disc should be replaced. Measure
the pad thickness using calipers or
measuring against the diameter of
the 1.5 and 2.0mm hex wrenches
provided with the model.
Piston/sleeve: The life of the piston and sleeve
will vary greatly with how the engine was used
and maintained. The piston and sleeve should be
replaced when they no longer seal effectively (loss of
compression). Symptoms include the engine being
difficult to start when warm, stalling when warm,
and stalling when throttle is suddenly closed to idle.
Replace the wrist pin and G-clip whenever the piston
and sleeve are replaced.
After-run Procedure
You must perform after-run maintenance on your
Traxxas engine whenever the model will be stored for
longer than a few hours. Taking the time to prepare
your engine for storage will reward you with longer
engine life, easier starting, and better performance.
When a nitro engine is shut off, some excess unburned
fuel remains in the engine. The methanol in model
engine fuel is hygroscopic, which means it easily
attracts and absorbs moisture. This moisture can cause rust and corrosion
on the steel engine parts (crankshaft, bearings, wrist pin and starter shaft)
if the fuel is not removed from the engine. There are after run oil products
available from your hobby dealer or you can use WD-40™, a common
household lubricant. To ensure your TRX 3.3 Racing Engine is protected
from internal corrosion, use the following procedure:
1. Whenever possible, shut off the engine by pinching the fuel line
closed. This allows most of the excess fuel to be consumed by the
engine. Be sure the throttle is in the idle position. You may have to
pinch the fuel line closed for several seconds before the engine stops.
2. Completely empty the fuel tank. Use your fuel-dispensing bottle to
suck out the old fuel. Do not mix the old fuel with your fresh fuel
supply. If you leave fuel in the tank, transporting or handling your
Slayer may cause fuel to run into the engine.
Maintaining and Storing Your Slayer
3. With the fuel tank empty and the throttle at the idle position, try to
start the engine. The engine will most likely start and run for a few
seconds as it uses up any fuel remaining in the engine and fuel lines.
4. Once the engine stops, clean the outside of the engine with
compressed air or spray motor cleaner. Once the engine is clean and
dry, remove the glow plug power wire, glow plug, and air filter.
5. Open the throttle fully and spray a one-second burst of WD‑40 into
the carburetor and into the glow plug hole (Caution! Wear safety
glasses to prevent spray from getting into your eyes). If you are using
after-run oil, follow the manufacturer’s instructions.
6. Place a rag or paper towel over the engine to catch any WD‑40 or
after-run oil that may come out the carburetor or glow plug hole.
7. Connect the EZ-Start controller to the model and spin the engine for
10 seconds.
8. Remove the rag or paper towel and repeat steps 5–7 two
more times.
9. Clean and re-oil the air filter so it will be ready for use next time. See
page 21 for air filter maintenance instructions.
10. Replace the glow plug, reconnect the glow plug power wire, and
reinstall the air filter.
Clearing a Flooded Engine
If the engine is primed for too long during startup, then it can become
flooded with fuel. When the engine is flooded it will no longer turn due to
excess fuel in the combustion chamber preventing upward movement of
the piston. Use the following procedure to clear a flooded engine:
1. Remove the blue glow plug wire.
Piston stuck at “top dead center” (TDC)
“Top dead center” is the position where the piston is at the very top of
the tapered sleeve. Occasionally an engine can get “stuck” at this position.
This is most likely to happen on new engines during break-in, but can
also happen at other times. If the engine is stuck at TDC, use the following
procedure to release the piston from the sleeve:
1. Remove the glow plug using the included tool
or 8mm (5/16”) nut driver and verify that the
piston is at the top of its stroke.
2. Turn the Slayer over and locate the flywheel
through the cutout in the chassis. Insert a
flat blade screwdriver as shown between the
chassis and flywheel. Using the chassis for
leverage, rotate the flywheel counterclockwise
by pressing down on the screwdriver. The
flywheel will turn, unsticking the piston from
the sleeve.
Top Dead Center
3. Put two or three drops of light machine oil into
the glow plug hole to lubricate the piston and
sleeve. Do not use too much oil. It will hydro-lock
the engine. Verify the starter will spin the engine
with the glow plug out.
Be sure to follow proper
maintenance and storage
procedures to avoid damage
to your engine and other
components of your Slayer.
Don’t put the fuel from your
tank back into your fuel
jug. Dispose of it properly,
following city or county
4. Rotate the flywheel so the piston is at bottom
dead center and replace the glow plug with
gasket. Reconnect the blue glow plug wire.
Always wear eye protection
when using compressed
air or spray cleaners and
5. You should now be able to start the engine
with the EZ-Start.
2. Remove the glow plug and gasket with the glow plug wrench supplied
with your model. A 5/16 or 8mm nut driver will also work.
3. Turn the model upside down and plug in the EZ-Start controller.
Denatured alcohol (available
from home centers and
paint supply stores) in a
spray bottle is an extremely
effective cleaner. Be sure
to wear safety glasses and
gloves when working with
denatured alcohol.
Bottom Dead Center
4. Push the EZ-Start button for several seconds to clear the engine
of excess fuel. Do not look into the glow plug hole while the
engine is spinning or you could spray fuel into your face!
5. Turn the model over and reinstall the glow plug and gasket.
6. Reconnect the blue glow plug wire to the glow plug.
7. Reconnect the EZ-Start controller.
8. Do not prime the engine. Pull the throttle to 1/2 throttle and push the
EZ-Start button. The engine should start immediately.
Slayer • 39
Advanced Tuning Adjustments
This advanced tuning guide will take you one step further into the
cutting edge technology that has been designed into Slayer. Follow
the instructions provided here to take advantage of Slayer’s maximum
performance potential.
Caster adjustment shims (2 front, 2 rear)
Caster Adjustment
The caster angle of the front
suspension may be used to adjust
the understeer (push)/oversteer
handling characteristics of the
model. Generally, increasing the
caster angle will move the truck
towards an oversteer condition
(more traction on the front tires, less
on the rear tires). Decreasing the
caster angle will create a tendency
towards understeer (pushing in the
turns). From the factory, the front
suspension is set to a caster angle of Ground plane
10-degrees. The rear caster angle is
Number & Position of Caster Adjustment
not adjustable. The caster angle
Shims (Front Upper Control Arm)
of the front suspension can be
In Front of
Behind Hinge
adjusted from 5° to 15°. Adjust
Caster Hinge Pin Boss
Pin Boss
the caster by positioning the
caster adjustment shims on the
upper control arms of the front
suspension as shown in the
table to the right.
40 • Slayer
Caster Angle, and Bump Steer
Bump steer is unwanted change in the steering angle of the front wheels
as the suspension travels up and down. It can result in unstable and
unpredictable handling. Bump steer is affected by the position of the
outer toe link end on the axle carrier. From the factory, the toe links are
positioned so that bump steer is virtually eliminated (about 3/100 of
a degree through the entire range of travel). When the caster angle is
changed, the outer toe link end should be repositioned on the axle carrier
to maintain zero bump steer geometry. Adjustment is achieved using the
shims and hollow balls provided with the vehicle. Refer to the Bump Steer
Elimination chart on page 41, and look up your caster angle setting to
find the correct position for the outer toe links. Positioning the toe-links
correctly will maintain the original factory geometry and eliminate the
unwanted steering angle changes caused by bump steer.
Roll Center
There are two holes on the
Upper Control Arm
Upper Mounting Holes
bulkheads to mount each upper
suspension arm. The roll center
of the vehicle can be raised by
mounting the upper control arm in
the lower of the two holes. This will
Upper Control Arm
Lower Mounting Holes
effectively increase the roll stiffness
of the vehicle (similar to installing
swaybars). Adding roll resistance to
one end of the vehicle will tend to
add traction to the opposite end. For example, increasing roll resistance in
the rear by installing the upper arms in the lower holes will provide more
traction for the front wheels and potentially more steering. Installing the
upper arms in the lower holes on the front and rear will increase overall
roll resistance without changing the handling balance. The arms are
installed in the upper position from the factory to make the truck easier
and more forgiving to drive and less likely to traction roll in turns. The
lower holes should be reserved for track tuning. Note: When the upper
suspension arms are moved to the lower holes, the front outer toe link
ends and the rear toe control links should be repositioned to eliminate
bump steer. Refer to the Bump Steer Elimination chart on page 41,
and look up your suspension combination (caster angle and roll center
position) to find the correct position for the front outer toe links and the
rear toe control links. Adjustment is achieved using the shims and hollow
balls provided with the vehicle.
Rockers (Progressive Rate/ Suspension Travel)
One of the most exciting aspects of Slayer’s suspension is the inboard
shock (damper) arrangement that uses pivoting rockers to translate
vertical wheel travel into linear shock motion. The rockers can be changed
to increase the progressive rate of the suspension.
The progressive rate determines how much the force at the wheel
produced by the springs being compressed (wheel force) will vary with
suspension travel (or vertical travel of the wheel). On a progressive
suspension arrangement, the wheel force will increase at a faster and
faster rate as the suspension is compressed. It feels as though the shock
spring gets progressively stiffer the more you compress the suspension.
On a linear suspension arrangement, the wheel force increases linearly as
the suspension is compressed. The spring does not feel any stiffer, even
when the suspension is fully compressed. This provides a very “plush”
feeling suspension with seemingly bottomless suspension travel.
Advanced Tuning Adjustments
Rocker Arm
Total Travel
Progressive Rate
Progressive 2
(40mm up / 20mm down)
Progressive 3
(40mm up / 20mm down)
There are two different rocker arm sets that are compatible with Slayer.
Both sets will allow the wheel to travel a total of 60mm in the vertical
direction. From the ride height position, the wheel will be able to travel
40mm in the upward direction (bump), and 20mm in the downward
direction (droop). The Slayer comes equipped with the Progressive 2
rocker set, which offers a good balance of progressive rate for predictable
body roll, brake dive, and high-speed stability.
Wheel Force
The Progressive 3 rocker arm set (available separately) uses a higher
progressive rate that will provide a firmer feel, reducing body roll, brake
dive and rear squat. Installation of the Progressive 3 rocker arm requires
the following parts:
#5359 Progressive 3 Rocker Arm Set
#5133 Pushrod Spacers (these are required to lengthen the pushrods to
maintain proper suspension travel.)
The chart below demonstrate the effect of the various rocker arms on
wheel force as the suspension is compressed. On the progressive rate,
wheel force is light at first and increases as the suspension is compressed.
Progressive Rate Travel
Constant Rate Travel
Wheel Travel
Bump Steer Elimination Chart
The illustrations and the following table detail the position of the outer
toe link end for various caster and roll center settings to eliminate bump
steer. The shims and the hollow balls used to adjust bump steer are
provided with your vehicle.
Outer Toe Link End Setup
5° 7.5° 10° 12.5° 15°
Control Arm
Mounting Hole on
Front Bulkhead
Hollow Ball
Thin Shim
Thick Shim
Thin Shim
Hollow Ball
Thick Shim
Tall Center
Hollow Ball
Thick Shim
Hollow Ball
Thin Shim
Thick Shim
Thin Shim
Hollow Ball
When the rear upper control
arms are mounted in the lower
of its two mounting holes in
the bulkhead (roll center), the
tall hollow ball should be used
as shown.
Outer Toe Link
End Setup
Control Arm
Mounting Hole on
Rear Bulkhead
Tall Center
Hollow Ball
Tall Upper
Hollow Ball
Slayer • 41
Advanced Tuning Adjustments
Shock Piston Hole Sizes
(Sold Separately) (Stock Front & Rear)
Never slide the threads on
the shock rod past the X-ring
seal when it is installed and
compressed by the bottom
cap of the shock. Doing so will
damage the seal and cause
shock oil to leak.
Shock Pistons
The shock pistons can be replaced
with the available optional pistons
to vary the amount of damping.
Optional pistons with bypass holes
that are larger (1.4mm) than the
factory installed stock pistons can
be used to decrease damping. From
the factory, Slayer is equipped with
1.3mm pistons in the front and rear.
Multi-tool Shock Functions
A. Tighten/Loosen Upper Cap
Shock disassembly
The shocks must be removed from
the vehicle and disassembled to
change the pistons. Use the shock
exploded views included with the
model to aid in the assembly process.
1. Remove the spring and lower
B. Tighten/Loosen Lower Cap
spring retainer from the shock.
2. Remove the shock cap (A) and
empty the shock body of shock oil.
3. Remove the lower cap (B) and
the X-ring from the shock body.
4. Use side cutters to grip the shock
shaft just above the rod end (C).
Remove the rod end from the
shock shaft using the suspension
C. Remove/Install Rod End
multi tool (C).
5. Remove the shock shaft with piston from the shock body
out through the top of the shock body.
Shock assembly
1. Replace the stock piston with desired
optional piston. Be careful not to lose the
small washer located below the piston.
2. Position the new piston onto the shock shaft
above the small washer. Grip the threads
of the shaft with side cutters or needlenose
pliers and tighten the nut with the 4-way
wrench to secure the assembly.
42 • Slayer
Piston Installation/Removal
3. Insert the shock shaft assembly through the shock body until the
piston bottoms out.
4. Lubricate the shaft and X-ring with silicone oil.
5. Install the X-ring over the shaft and into the bore of the shock body.
6. Install the lower cap using the suspension multi tool (B).
7. Slide the bump stop onto the shaft.
8. Grip the shaft close to the threads with needle nose pliers or side
cutters and thread the rod end onto the shock shaft until the rod
end bottoms out (C).
9. Fill the shock with new silicone shock oil up to the top of the
shock body. Slowly move the piston up and down (always keeping
it submerged in oil) to release the air bubbles. Let the shock sit for a
few minutes to allow any remaining air bubbles to surface.
10. Slowly thread the upper cap with the installed shock bladder onto
the shock body with the suspension multi tool (A). The excess oil will
bleed out of the small hole in the shock cap. Tighten the shock cap
until snug. Use the included steel shock wrench to hold onto shock
body while tightening.
11. Reinstall the spring and lower retainer.
Adjusting the Gear Ratio
The gear ratio on Slayer can be adjusted for different conditions that may
require either increased acceleration or increased top speed. Adjusting
the gear ratio is accomplished by changing the clutch bell on the engine
and/or the spur gear (slipper clutch gear) on the transmission. From the
factory, Slayer is equipped with a 15-tooth clutch bell and a 36-tooth
spur gear. This combination will provide a good balance of acceleration
and top speed. Optional spur gears and clutch bell gears are listed
on your parts list. Refer to the chart on page 43 for possible gearing
Adjusting the Two-Speed Ratios
Slayer is equipped to allow adjustment to the two-speed by installing
optional close and wide-ratio gearsets. This requires transmission
removal and disassembly (see Traxxas.com for detailed instructions).
The close ratio gearsets will reduce top speed slightly but will provide
more powerful acceleration by reducing engine rpm loss when shifting
from 1st gear to 2nd gear. The wide ratio gear set is installed in the
Slayer. The additional horsepower and torque output of the TRX 3.3
engine provides seamless shifting even with the larger gap between
first and second gears.
Advanced Tuning Adjustments
The following gear ratio chart shows the available combinations with
optional spur gears, clutch bells, and two-speed gear sets.
Gear Ratio Chart
With 14T Clutch Bell
# of Spur Gear Teeth
16.87 17.81 18.75
11.70 12.35 13.00
16.87 17.81 18.75
12.75 13.46 14.17
16.87 17.81 18.75
10.77 11.37 11.97
With 15T Clutch Bell (standard) # of Spur Gear Teeth
2nd gear sets
With 16T Clutch Bell
2nd gear sets
With 17T Clutch Bell
2nd gear sets
the differentials. Changing to a higher viscosity oil in the differential will
reduce the tendency for engine power to be transferred to the wheel
with the least traction. You may notice this when making sharp turns
on slick surfaces. The unloaded wheels on the inside of the turn have
the least traction and tend to spin up to extremely high rpms. Higher
viscosity (thicker) oil causes the differential to act like a limited-slip
differential, distributing more equal power to the left and right wheels.
Slayer will generally benefit from higher viscosity oil when climbing, rock
crawling, or racing on low traction surfaces. Note: Heavier oil will allow
power to be transferred even with one or more tires off the ground. This
can make the vehicle more likely to overturn.
Use higher viscosity
(thicker) oil for:
From the factory, both the differentials are filled with SAE 30,000W
viscosity silicone oil. Only use silicone oil in the differentials. Traxxas
sells SAE 10,000W and SAE 50,000W viscosity oil (see your parts list). The
differentials have to be removed from the vehicle and disassembled to
change/replace oil.
• More power to the wheels
with least traction.
• Racing on low-traction
rough surfaces.
• More power to the wheels
with the most traction.
• Racing on low-traction
smooth surfaces .
• Better performance for
climbing on uneven terrain.
Using lower viscosity
(thinner) oil for:
# of Spur Gear Teeth
14.76 15.58 16.40
10.24 10.81 11.38
14.76 15.58 16.40
11.16 11.78 12.40
14.76 15.58 16.40
9.95 10.47
# of Spur Gear Teeth
13.89 14.67 15.44
9.64 10.17 10.71
13.89 14.67 15.44
10.50 11.09 11.67
13.89 14.67 15.44
*stock configuration out of the box
Tuning The Sealed Gear Differentials
Slayer’s front and rear gear differentials allow the left and right
wheels to spin at different speeds while turning so that the tires do
not scuff or skid. This decreases the turning radius and increases
steering performance.
The performance of the differentials can be tuned for different driving
conditions and performance requirements. The differentials are filled
with silicone differential fluid, and are sealed to maintain consistent
long-term performance. Changing the oil in the differential with either
lower or higher viscosity oil will vary the performance characteristics of
Slayer • 43
owners manual
MODEL 5908
1100 Klein Road, Plano Texas 75074
080812 KC1151
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