2007 Nitro Stampede Operating.in1 1
Part #4199X
Rev 070402
4/2/07 5:00:45 PM
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.
Thank you for purchasing the Traxxas Nitro Stampede®. This
manual contains the instructions you will need to operate and
maintain your Nitro Stampede. Look over the manual and examine
the Nitro Stampede carefully before running it. If for some reason
you think the Nitro Stampede is not what you wanted, then do not
continue any further. Your hobby dealer absolutely cannot accept
a Nitro Stampede for return or exchange after it has been run.
Please read all of the operating instructions and precautions
before attempting to drive the Nitro Stampede. Even if you are
an experienced R/C enthusiast, continue reading to learn about
Nitro Stampede’s unique features. Pay special attention to the
mechanical and safety precautions outlined in the manual.
If you have any questions about your new model, feel free to call
Traxxas’ technical support line toll-free at 1-888-TRAXXAS (1-888872-9927) Outside the U.S. call 972-265-8000. Technical support
is available Monday through Friday, from 8:30am to 9:00pm
Central time. Technical assistance is also available through our
website at www.Traxxas.com (e-mail us at support@Traxxas.com).
We hope that you will enjoy many hours of fun with your new
Nitro Stampede.
Fuel is the most critical component for making your engine
perform properly. Improper fuels will cause hard starting, poor
performance, and excessive wear on the engine. For the best
performance from your TRX® Pro.15 engine, use Traxxas Top
Fuel.® Traxxas Top Fuel is the only model engine racing fuel which
exceeds all of the Traxxas engine warranty requirements. It is
specially formulated to resist
heat, and is guaranteed to
provide the best performance
and longest life from your
Traxxas engine. Top Fuel uses
superior natural and synthetic
lubricants in just the right
amounts to deliver the crisp,
clean throttle response and
screaming top-end performance
you want in a car fuel, without
sacrificing long-term durability.
Top Fuel’s consistency and
reliability has been proven in thousands and thousands of
engines so you can trust it in your engine with confidence.
Traxxas cannot guarantee the quality and consistency of other
manufacturers’ fuels.
Some fuels are capable of destroying your TRX Pro.15 engine! If you
must use a fuel other than Traxxas Top Fuel contact Traxxas first, at
1-888-TRAXXAS, to find out if the fuel is safe for use with TRX engines.
Fuel is usually purchased by the gallon
or quart, so a smaller bottle with a
dispensing tube is required to fill the
fuel tank. The fuel tank in the Nitro
Stampede has a capacity of 75cc. The
fuel bottle should always be capped
to prevent the fuel from evaporating
and becoming contaminated with
debris or moisture. The alcohol and
nitro contents of the fuel will evaporate,
thus upsetting the fuel balance and
spoiling the fuel. Do not use old or
dirty fuel!
Part #5001-Fuel Bottle
Every precaution outlined in this manual needs to be followed to
help ensure safe operation. Operate your model sensibly and with
care and it will be exciting, safe, and fun for you and your spectators.
Failure to operate your model in a safe and responsible manner could
result in property damage and serious injury. You alone must see to it
that the instructions are followed and the precautions are adhered to.
The Nitro Stampede is not intended for use by children without the
supervision of a responsible adult. Traxxas shall not be liable for
any loss or damages, whether direct, indirect, special, incidental,
or consequential, arising from the use, misuse, or abuse of this
product and any chemical or accessory required to operate
this product.
• Nitro Stampede is very fast! Children under 16 years of age and
inexperienced drivers should not operate the Nitro Stampede
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.
• 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 Nitro Stampede
outdoors, in a well-ventilated area. Never run the engine indoors.
• Do not operate your Nitro Stampede at night, or anytime your line of
sight to the model may be obstructed or impaired in any way.
• Never operate your Nitro Stampede in crowds of people or busy
pedestrian areas. Nitro Stampede 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.
• Because Nitro Stampede is controlled by radio, it is subject to radio
interference from many sources beyond your control. Since radio
interference can cause momentary loss of control, always allow
a safety margin in all directions around your model to prevent
• The engine can be loud. If the noise makes you uncomfortable, wear
ear protection. Be considerate of your neighbors by not running your
model early in the morning or late in the evening.
• Most importantly, use good common sense at all times.
Previous experience with radio controlled models
is recommended. Models require a higher level of
setup, maintenance, or support equipment.
To operate the Nitro Stampede, you will need these additional items.
All of these items should be available from your hobby shop.
1. 12 “AA” size batteries for your transmitter (8) and receiver (4)
2.NiCad or NiMH 7.2V battery pack and charger for the EZ-Start®
3.Small Phillips head and flat screwdrivers (for adjustments)
4.After-run oil (to protect the engine from corrosion)
5.Spare glow plugs (standard plug, Traxxas part #3230; or heavy-duty plug, Traxxas part #3231)
6.In-line fuel filter (recommended)
7.Spare fuel line (recommended)
Throttle Neutral Adjust
Steering Wheel
Throttle Trim
Steering Trim
Throttle Trigger
The Nitro Stampede is equipped with the 2-channel TQ radio
system. The following radio system terms will be used throughout
the rest of these operating instructions.
Channel - The 27 MHz (megahertz) frequency band is divided
into six 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.
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 on which
channel the radio system will operate. For each channel, there are
two crystals, one for the receiver and one for the transmitter. Of
those two crystals, the one marked “RX” 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 Nitro Stampede. All Traxxas RTR models
operate on a 27 MHz frequency band.
mAh – Abbreviation for milliamp hour. Measure of the capacity of
the battery pack. The higher the number, the longer the battery
will last between recharges.
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 Nitro Stampede that receives
signals from the transmitter and relays them to the servos.
Servos - Small motor units in your Nitro Stampede that operate the
throttle and steering mechanisms.
Two-channel radio system - The TQ radio system, consisting of
the receiver, the transmitter, and the servos. The system uses
two channels: one to operate the throttle and one to operate
the steering.
Power Switch
Servo Reversing Switches
Steering (R), Throttle (L)
Power Indicator
Transmitter - The hand-held radio unit that sends throttle and
steering instructions to your Nitro Stampede.
Trim - The fine-tuning adjustment of the neutral position of the
servos, made by turning the throttle and steering trim knobs on
the face of the transmitter.
PART# 3170
Install 8 “AA” batteries into the bottom of the transmitter as shown
in the drawing.
2007 Nitro Stampede Operating.in3 3
4/2/07 5:00:46 PM
The receiver battery holder is
located underneath the battery
cover. Remove the battery cover
by removing the two body clips
from the posts on both sides of
the battery holder. Install four
“AA” batteries into the battery
holder. Alkaline batteries should
be used. Place the
battery holder into
the battery cover with
the cushioning foam.
Secure the battery
cover to the chassis
using the two body
clips as shown.
2. Always turn the transmitter
on first and off last. This
will prevent the model from
receiving stray signals and
running out of control. Slide the
transmitter switch to the “on”
position. A steady red light should illuminate. A flashing red
light indicates weak batteries. Weak batteries will limit the range
of the radio signal between your transmitter and receiver. Loss of
the radio signal can cause you to lose control of the truck.
3. Turn the truck on. The
switch is located on the
chassis. The servos should
jump and move to their idle
(neutral) positions.
Never turn the transmitter or receiver off while the engine is
running. The model could run out of control. (The on/off switch
only turns the receiver on and off. It does not turn off the engine.)
Locate the plastic tube
and the antenna tip
(supplied in the bag
with your instructions).
Insert the black antenna
wire, extending from the
receiver housing, into one
end of the tube and push
it all the way through.
Spray the wire with glass
cleaner to make it easier
to insert Insert the tube into the antenna mount in the side of the
chassis. Fold the remaining antenna wire over the top of the
antenna tube and secure it with the vinyl antenna tip.
4. With the front wheels off the
ground, operate the steering
control on the transmitter
(channel 1). Check for rapid
operation of the steering
servo and that the steering
mechanism is not loose or
binding. If the servo operates
slowly, check for weak
batteries. Turn the “steering
trim” control on the transmitter to adjust the servo so that the
front wheels are pointing straight ahead. Check to be sure that
the wheels do not turn more in one direction than in the other.
Under no circumstances should you ever cut your antenna wire.
Its length is specially tuned to the frequency band, and cutting it
could severely shorten the radio’s range. On the transmitter, fully
extend the chrome telescopic antenna.
Your radio system was pre-adjusted before it left the factory, however,
the adjustment should be checked prior to running the truck.
1. Before you ever turn your radio system on, you must “clear”
your frequency. There are six different channels numbered 1
through 6. Each of the six channels is represented by a color.
Look at the crystal in the back of the transmitter to determine
on which of the channels your truck is operating. Clearing your
frequency means checking to be sure that no one else in the
area is operating on the same channel.
Wheels pointing straight ahead
5. Operate the throttle trigger on the transmitter to ensure that
the throttle servo is operating properly. When the servo is
in the neutral position, the carburetor should be in its idle
position (you will adjust the engine idle speed later). When the
throttle trigger is pulled all of the way, the carburetor should
be in the fully-open position. When the throttle lever is pushed
forward, the brake should be locked and the throttle should
not close any further than when at idle.
Throttle Neutral Adjust
The throttle neutral adjustment
is located on the transmitter
face and controls the forward
and reverse travel of the throttle
trigger. There are two settings,
50% SE
50/50 which allows equal travel
for both forward and brake, and
70/30 which allows more travel for
throttle and less for brake. Change
the adjustment by pressing
the button and sliding it to the desired position. 50/50 is the
recommended setting while running the Nitro Stampede.
Servo Reversing Switches
On the front of the transmitter there are two switches. One for
throttle and one for steering. Moving the switches reverses the
direction of the corresponding servos. For example, if you turn
your steering wheel right and the model moves left, then switch
the steering servo
reversing switch to
correct the servo
direction. You may
need to adjust the
trim control after
moving the servoreversing switch.
There are many things such as buildings, power lines, radio
transmitters, etc. which can adversely affect the performance of
your radio system. To make sure you do not have a “runaway”
model, range test the radio system. With the radio system on and
working, hold the truck and have a friend carry the transmitter
away from you the distance you plan to run the truck. Have the
friend operate the controls on the transmitter to be sure that
everything is working at full range.
If the Motor LED fails to light and the starter
fails to operate, then the EZ-Start is in
protection mode.
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:
Your EZ-Start controller plugs into a 4-prong receptacle on the battery
cover of your Nitro Stampede. 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.
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 three 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.
Your carburetor has been factory preset for break-in. Do not
re-adjust your carburetor settings unless you suspect a
problem. The following steps are for reference only.
High-Speed Mixture Setting
The high-speed mixture screw controls how much fuel enters the
engine during mid and high-speed operation. Turn the high-speed
mixture screw clockwise, by hand, until it stops (Do not tighten
or the needle may be damaged). Now, turn the mixture screw
counterclockwise 2 1/2 complete turns.
Setting the Idle Speed
The idle screw regulates the throttle
opening to control the idle speed.
The throttle opening at idle should
be set as shown in the drawing.
The opening should be 1 to 1 1/2
millimeters at the widest point in
the opening. The engine may not
idle well until it is warmed.
Filling the Fuel Tank
Use a small fuel bottle or bulb to put fuel into the tank. Only fill
the tank to the bottom of the fill neck. The Nitro Stampede can be
carefully refueled while the engine is running.
1. Press the tab in the end of
the battery compartment
door to open. (A)
2. Plug a fully charged 7.2volt battery pack into the
connector inside. (B)
3. Twist the battery 2 or 3 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)
Installing the Air Filter
Remove the protective cap from the carburetor
air intake. Install the rubber air filter base and prelubed foam element onto the carburetor intake.
The foam air filter element may be cleaned and
reused. Always be sure the filter element is oiled
properly before running the engine. For the best
filtration, use the type of oil made for foam air
filters. Traxxas air filter oil is recommended (part
#5263). Lightweight motor oil or after-run oil may
also be substituted. When the element gets dirty, clean it with
dish soap and rinse. Next, saturate it with oil and then squeeze
out the excess oil.
Low-Speed Mixture Setting
This screw meters the fuel at low
speeds. The low-speed mixture
screw is located in the end of the
carburetor, inside the throttle arm.
This screw controls how much
fuel enters the engine at idle and
low throttle. This adjustment will
smooth the idle and improve
acceleration to mid-speed. Make
this adjustment with the throttle closed, after setting the idle.
Gently turn this screw clockwise until it stops against the needle seat.
Be very careful, it’s difficult to know when the needle has seated due
to the thread holding material on the needle’s thread. Overtightening
of the screw may result in damage to the needle seat. Now turn the
low-speed mixture screw counterclockwise 1 3/4 turns.
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.
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.
Shutting Off the Engine
Before starting the engine it is important to know how to shut it off.
The correct method is to pinch and hold the carburetor’s fuel line at
idle speed, until the engine dies.
Starting the Engine
Before you start your engine for the first time, make sure you have read
all instructions and precautions in this manual. Pay close attention to
the 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 model indoors until you’re
ready to start it and then take it outside. We do not recommend
running the model in temperatures below 35° F.
1. Turn on the radio system.
2. Make sure the throttle trigger on the transmitter is in the idle
(neutral) position.
3. Connect the EZ-Start® controller.
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 pressing the primer
button (built into the fuel tank)
several times until the fuel moves
through the fuel line towards the
carburetor. Be sure to watch the
fuel line going into the carburetor
closely to see when the fuel reaches
the carburetor. Once it reaches the
carburetor, press the primer button
one more time. If you press the
primer button too many times, you
will flood the engine and the EZ-Start
will not be able spin it over.
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).
Once your engine is running, it must be broken-in. The key to
breaking in your engine is patience. The break-in time will take
about 1 to 11/2 hours. During the break-in period, your engine
may appear to malfunction with symptoms such as stalling,
inconsistent performance, and fouled glow plugs. Don’t give up
on it! These are just “break-in pains” that every new engine has
to go through. They will disappear once you get through the
break-in period. Just keep it running, and throttle on and off as
smoothly as you can. Sudden bursts or releases of the throttle can
stall your engine. Resist the temptation to tune the engine
for performance and/or run for extended times at wide open
throttle. Soon, after about the fourth tank of fuel, your patience
will pay off with solid, consistent performance.
During Break-in...
•Special break-in fuels are not required.
•Drive the model on a smooth hard surface.
•If possible, avoid running on very hot, humid days.
•Run with the body off for extra engine cooling.
•Turn the mixture screw (needle) clockwise (in) to lean the mixture
and counterclockwise (out) to richen the mixture.
•Do not allow the fuel tank to run completely empty, possibly
leading to a burned plug. An extremely low fuel level causes the
fuel mixture to be too lean.
•Keep extra glow plugs handy. The break-in process, because of the
engine running rich, can cause deposits to form on the glow plug,
leading to failure.
The First Tank of Fuel
Drive the Nitro Stampede on a flat paved surface in an oval
configuration. This will cause you to naturally vary your speed over
the entire rpm range. During this break-in time ease in and out
of the throttle slowly to avoid stalling the engine. The goal is to
simply keep it running. The fuel mixture setting may require slight
adjustment to correct for different altitudes and temperature. To tell
if the engine is running rich (high volume of fuel flowing through
the engine) look for the following conditions:
1. The engine should accelerate sluggishly.
2. There should be a thick trail of blue smoke coming from
the exhaust.
3. If you do not observe the conditions above, then turn the highspeed needle out 15° (counterclockwise) and retest.
4. Do not rev the engine with the wheels off the ground. High, noload rpm can damage the engine, usually resulting in a broken
connecting rod. At the end of the first tank of fuel, stop the
engine and allow it to cool for 5-10 minutes before proceeding.
Tanks Two Through Four:
2 / turns out
Shut off the engine and
allow it to cool for 5-10
minutes, then refuel. Turn
the high-speed needle in
15° (clockwise). Turn on the
radio system and restart
the engine. Continue driving
on your oval course, varying
your throttle, until the second
tank of fuel is used up. Repeat
2 turns out
this process for tanks three
and four. Important: Do not lean the high-speed mixture less than
2 turns out from closed (see illustration). Also, be sure to allow
the engine to cool between each run.
• The radio system is not waterproof. Avoid driving through puddles,
wet grass, or mud. Water could damage the electronics.
• Do not continue to operate the Nitro Stampede with low batteries.
After the battery power drops below a certain point, the model
will continue with the last command it had from the transmitter.
Indications of low battery power include slow operation and
sluggish servos. On the transmitter, a flashing red light indicates
low transmitter batteries.
• Do not drive the Nitro Stampede at night, on public streets, or in
large crowds of people.
• If the truck becomes stuck, do not continue to run the engine.
Remove the obstruction before continuing to drive.
• Do not attempt to push or tow objects with the Nitro Stampede.
• The model is controlled by radio. It is subject to radio
interference from many sources beyond your control. Since radio
interference can cause momentary losses of control, allow a
safety margin around the truck in order to prevent collisions.
• Use common sense whenever you are driving your model.
Intentionally driving in an abusive and rough manner will only
result in poor performance and broken parts.
Tuning Your Engine for Best Performance
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). Leaning the engine beyond
the safe allowable limits will result in poor performance and engine
damage. Indications of an overly lean mixture include:
• Cutting out or sudden loss of power during acceleration.
• Overheating (temperature beyond 300° 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 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.
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.
• 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 with the Nitro Stampede after each adjustment to clear
out the engine and note any change in performance. Continue this
procedure until one of the following conditions exists:
1.There is no longer any performance improvement
2.The engine begins to cut out at high-speed
3.There is a sudden loss of power during acceleration
4.The engine begins to overheat (see Tuning the Engine by
Temperature for symptoms of overheating).
If any one of the above conditions occurs, the fuel mixture is already
past the maximum safe lean setting. 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 will be set using the pinch test.
1.Once the engine is warm, do several high-speed runs to confirm that
the high-speed needle is set correctly.
2.Bring the vehicle in and pinch closed the fuel line going into the
carburetor. The engine should run for 2-3 seconds, speed up, and
then die.
3.It is very important to make several high-speed runs with the Nitro
Stampede 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.
4.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.
5.If the engine dies immediately without speeding up, then richen the
low-speed needle 1/8 turn, make several more high-speed runs,
and retest.
6.If the engine dies when you try to accelerate abruptly, then the lowspeed needle is probably set too lean. Richen the low-speed needle
1/8 turn, make several more high-speed runs, and retest.
7.When the low-speed needle is set correctly, the engine’s throttle
response should be very quick.
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 temperature.
1.Turn the throttle trim on the transmitter so that the brakes are
applied. This ensures that the throttle barrel is resting against the idle
adjustment screw.
2.If necessary, remove the air filter to gain access to the idle
adjustment screw.
3.Turn the screw clockwise to reduce the idle speed, or
counterclockwise to increase it. The idle speed should be
set as low as possible while still maintaining reliable running
4.Reset the throttle trim on the transmitter.
Fine-Tuning the Carburetor
After fine-tuning your engine at the end of the break-in 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.
If the...
Nitro %
then the air density is...
Slightly more dense
Slightly less dense
Less dense
More dense
More dense
Less dense
More dense
Less dense
the overall mixture should be...
Slightly richer
Slightly leaner
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
Part #4091
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 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
windshield. 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.
Geometry and alignment specs play an important role in your
truck’s handling, so take the time to set them correctly. Set the
steering trim on your transmitter to neutral. Now, adjust your
tie rods so that both wheels are pointing straight ahead and
are parallel to each other (0 degrees toe-in). This will ensure
the same amount of steering in both directions. If you run
out of adjustment, then the steering servo will have to be recentered (see “centering your servos” on page 9). For increased
stability add 1-2 degrees of toe-in to each front wheel. Use the
turnbuckles to adjust the alignment.
from 10W to 50W (available from your hobby shop). The thinner
viscosity oils (30W or less) flow more smoothly and are more
consistent, while thicker oils provide more dampening. Use only
100% pure silicone shock oil to prolong seal life.
The ride height for Nitro Stampede can be adjusted by adding or
removing the clip-on spring pre-load spacers. Instead of adding
spacers to increase stiffness, use stiffer springs. Adjust the ride
height so that the suspension arms are slightly above being parallel
to the ground. Observe how the Nitro Stampede handles in turns.
If it is picking up the inside rear wheel in hard turns, then stiffen
the front suspension. If it is picking up the inside front wheel in
hard turns, then stiffen the rear suspension. Proper set-up will
add stability and help prevent roll-overs.
Gear Ratios
A unique Nitro Stampede feature is the ability to change the gear
ratios. The final drive ratio of the gearbox is 3.75 to 1. Use the
following formula to calculate the overall ratio:
Number of Spur gear teeth
Number of Clutch Bell gear teeth
x 3.75 Final drive ratio
Nitro Stampede comes with a 66-tooth spur gear and a 18-tooth
pinion (clutch bell) gear. This combination will provide the best
overall acceleration and top speed. If you want more acceleration
and less top speed, then use a smaller clutch bell gear (fewer
teeth). For more top speed, use a larger clutch bell gear.
Changing the Clutch Bell and Spur Gears
The camber angle of both the front and rear wheels can be
adjusted with the camber rods (upper turnbuckles). Use a square
or right-angle triangle to set the camber accurately. Adjust the
front wheels to 0 degrees of camber (wheel perpendicular to
the ground). In the rear, adjust the wheels to 1 to 2 degrees of
negative camber. These adjustments should be set with the truck
positioned at its normal ride height.
Positive camber Negative camber
The four shocks on Nitro Stampede
have the most influence on its handling.
Whenever you rebuild your shocks, or
make any changes to the pistons, springs
or oil, always do it carefully and in pairs
(front or rear). Piston head selection
depends on the range of oil viscosities
that you have available. For example,
using a two-hole piston with a lightweight
oil will, at one point, give you the same
dampening as a three-hole piston with
heavier oil. We recommend using the twohole pistons with a range of oil viscosities
Remove the rubber exhaust pipe
and the tuned pipe. Remove the
electric starter drive. Loosen the four
3x8mm cap-head screws which hold
the slotted adjusting plates to the
engine mount.
Remove the 4mm nylon locknut and
the spring from the slipper clutch. Try
to remove the slipper clutch as one
assembly by holding the pressure
plates together with your thumb and
index finger.
Remove the large E-clip on the clutch
shaft and the clutch bell gear. Remove
the ball bearings and install them in
the new clutch bell gear. Reinstall
the clutch bell gear and E-clip. Note:
Smaller clutch bell gears use smaller
ball bearings. Refer to your parts list
for the correct bearings. Reinstall the
spur gear on the top shaft and secure
it with the 4mm locknut.
Slide a strip of thin note paper
between the spur gear and the clutch
bell gear. Push the clutch bell gear
against the spur gear and tighten
the 3x8mm adjusting plate screws.
Remove the paper and the gear mesh
should be correctly adjusted.
Adjusting the Slipper Clutch
The Nitro Stampede features an adjustable slipper clutch on the
spur gear to protect the drivetrain from sudden shock loads (such as
landing off of jumps with the engine at full throttle). Under normal
conditions the slipper clutch should not slip. Before adjusting the
slipper clutch, turn the model off. Do not adjust the slipper clutch
while the engine is running.
Use the supplied wrench to tighten the slipper nut (clockwise) until
it stops and then back the nut out 1/4 of a turn. If you notice any
decrease in performance after making changes to the slipper clutch
adjustment, then it may be too loose. The slipper must not be allowed
to slip during normal acceleration or the slipper could be damaged.
Centering your Servos
Whenever your radio system has been removed for service or
cleaning, the servos must be re-centered prior to installing the
radio system in the model. If the radio system is installed in the
truck, disconnect the servo horns from the servos.
Connect the steering servo to channel 1 on your receiver and the
throttle servo to channel 2. The white wire on each servo cable is
positioned towards the crystal. Connect the red and black cable
from the battery holder to the “batt” terminal on the receiver. The
red wire is positive and the black wire is negative.
Place fresh “AA” batteries in the transmitter and turn the power
switch on. Slide the throttle and steering trim adjustments to the
center position. Now install fresh “AA” batteries into the battery
holder and turn the power switch to the “on” position. The servos
will automatically jump to their center positions. Turn off the
battery holder switch followed by the transmitter. The servos are
now ready to be installed. Be careful not to move the servo shaft
when reinstalling the servo horns.
You must perform after-run maintenance on your 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 engine is protected from internal corrosion,
use the following procedure:
1. 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
model may cause fuel to run into the engine.
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.
10. Replace the glow plug, reconnect the glow plug power wire, and
reinstall the air filter.
Nitro Stampede 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 5. 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.
• Tighten the wheel nuts (especially on the left side).
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.
• 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 on engine’s usage
and the quality and frequency of the engine maintenance. Inspect the
connecting rod after three gallons of fuel have been used.
• Slipper clutch pads (friction material): The slipper clutch pegs will
wear over time and require replacement. The life of the pegs depends
on how the slipper clutch was adjusted and how the Nitro Stampede
was used. If the slipper will not tighten or you are seeing signs of wear
on the face of the gear, then the pegs should be replaced.
• 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.
The troubleshooting guide on the following pages has been
provided to help you in diagnosing and repairing common engine
problems. Most difficulties with engines can be traced back to
problems with adjustment, fuel quality, dirt blockage, or common
parts that wear with everyday use.
Flooded Engine
The engine can become flooded if it is primed too many times
during the course of a routine start up. When the engine is
flooded, the EZ-Start® cannot turn the engine and it will appear to
be locked. Use the following procedure to clear a flooded engine.
1. Remove the blue glow plug wire
2. Remove the glow plug with a 5/16 or 8mm nut driver
3. Plug in the EZ-Start and turn the truck upside down
4. Push the EZ-Start button for several seconds to clear the excess
fuel from the combustion chamber
5. Turn the truck over and re-install the glow plug with gasket
6. Reconnect the blue glow plug wire
7. Remove one of the motor wires from the EZ-Start motor
8. Push the EZ-Start button for several seconds. This lights the
glow plug and burns off any remaining fuel
9. Reconnect the EZ-Start motor
10.Do not prime the engine. Partially open the throttle and press
the EZ-Start button. The engine should start immediately.
Glow Plugs
The glow plug in your engine is a consumable item which
must be replaced periodically to maintain peak performance
and starting ease. To test for a leaking glow plug, place a few drops
of fuel around the base of the glow plug when the engine is cool.
With the engine running, look for bubbles around the glow plug. If
the gasket is leaking, tighten the plug or replace the gasket.
If the “Glow Plug” LED fails to light, the glow plug may be bad
or broken. However, glow plug performance can deteriorate
significantly before the element actually burns in two. The only
sure way to test for a faulty glow plug is to replace it with a new
one to see if the problem goes away. You can view the glow
plug element by removing it and touching it against the engine
head while pressing the EZ-Start button. The glow plug will not
light unless it is grounded against the engine. Glow plugs can be
damaged by particles in the combustion chamber or by running
the fuel mixture excessively lean.
Traxxas makes three glow plugs. The standard hot plug (part
#3230) is the stock replacement plug for TRX® Pro.15 engines.
The optional heavy-duty (part #3231) and super-duty (part #3232)
plugs will last longer in most cases, however, it is a medium
temperature plug so performance may be reduced slightly. Do not
use plugs with idle bars!
Dirt is the main enemy to your carburetor. If you notice a sudden
change in the fuel mixture (lean) and performance of your model,
you may have dirt lodged in the carburetor. To dislodge a dirt
particle in your carburetor try screwing the high-speed needle all
the way in and then back out to its original settings. If the engine
doesn’t return to normal operation, then try backing the mixture
screw out and priming the engine to force fuel through the
carburetor. Return the mixture screw back to its original settings.
The engine will be flooded at this point so follow the directions
for relieving a flooded engine. If this fails, then the carburetor will
need to be removed and cleaned with denatured alcohol. Do
not blow on carburetor passages or fuel lines with your mouth.
Fuel and solvents are extremely poisonous. To prevent this from
occurring again, insert a fuel filter in the line between the tank and
the carburetor.
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 an 8mm (5/16”) nut driver and
verify that the piston is at the top of its stroke.
2. Use a flat blade screwdriver to rotate the flywheel. Place the
blade of the driver into one of the grooves of the flywheel
and push down, turning the flywheel counterclockwise when
viewed from the front. The flywheel should turn, freeing the
piston from the sleeve.
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.
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.
5. You should now be able to start the engine with the EZ-Start.
Electronic Components
Traxxas electronic components are warranted to be free from defects in
materials and workmanship for a period of thirty (30) days from the date of
purchase. Electronic components consist of the radio system (transmitter,
receiver, servos, switches, AC chargers, adapters, and receiver battery holders),
and any other Traxxas electronic component. See the additional limitations
that apply.
Chassis and Engine
The chassis consists of all remaining parts of the model that are not considered
electronic or part of the engine. This includes recoil starters, the EZ-Start®
system and controller, starter components, and the glow plug.
The Nitro Stampede is considered to be a race oriented, hobby-class model.
We have made every effort in component design, material selection, and
assembly to make our products as durable as possible. Because our products
are high-performance hobby-class models that operate at a much higher level
of performance than a “toy,” require periodic maintenance, and are intended
to be used in high performance applications over an extremely wide range of
running conditions and situations, no warranties are expressed or implied that
cover damage caused by normal use or wear, or cover or imply how long any
chassis or engine part will last before requiring replacement due to wear. Parts
will wear from use and occasionally require replacement. Engines and chassis
are only covered against manufacturer’s defects in materials, workmanship or
assembly when they are new (before being used).
If any component is found to be defective, incorrectly made, or incorrectly
assembled within the warranty coverage time period (where applicable), it will
be repaired or replaced at Traxxas’ sole discretion. This will be done within a
reasonable time period and free of charge. If you believe a defect in materials,
workmanship, or assembly was not apparent when the product was new and
only became evident after the product was used, then please call us at 1-888TRAXXAS. We stand behind our products and reputation and pledge to do our
best to make sure you are satisfied with your Traxxas product.
Any and all warranty coverage does not cover replacement of parts and
components damaged by abuse, neglect, improper or unreasonable use,
crash damage, water or excessive moisture, chemical damage, improper or
infrequent maintenance, accident, unauthorized alteration or modification,
use of improper fuels, or items that are considered consumable. Traxxas will
not pay for the cost of shipping or transportation of a defective component
from you to us.
Your Hobby Dealer’s Role
All warranty claims are handled directly by Traxxas. Your dealer can assist
you in contacting Traxxas and determining which components might be
defective, but he is under no obligation to provide free replacement parts
or service. Traxxas does not authorize dealers to make over-the-counter
exchanges or refunds for Traxxas products that have been used. Traxxas will
make the sole and final determination if a product or component can be
covered under warranty.
Limitations of Liability
Traxxas makes no other warranties expressed or implied. Traxxas shall not be
liable for any special, indirect, incidental, or consequential damages arising
out of the assembly, installation, or use of their products or any accessory or
chemical required to use their products. By the act of operating/using the
product, the user accepts all resulting liability. In no case shall Traxxas’ liability
exceed the actual purchase price paid for the product. Traxxas reserves the
right to modify warranty provisions without notice. All warranty claims will
be handled directly by Traxxas. The Traxxas warranty gives the customer
specific legal rights and possibly other rights that vary from state to state. The
customer is required to fill out and return the Registration Card enclosed with
the product as a condition of the coverage and performance of the warranty.
All dollar amounts stated are in United States dollars. The term “lifetime”
shall refer to the product’s production life at Traxxas. Traxxas is not obligated
to provide upgraded products at a reduced rate when a previous product’s
production cycle has ended.
To Obtain Warranty Service:
Call us first! Before you begin the process of obtaining warranty or repair
service, please call us at 1-888-TRAXXAS and speak with one of our friendly
and knowledgeable support technicians. Often a product might appear
defective, or to malfunction, only because it is being used improperly or
requires a simple adjustment. One phone call to our experienced support
staff just might get you back running quickly and easily!
When you return a product to Traxxas, please provide the following:
• Proof of purchase indicating the date purchased
• Any applicable forms
• Return address
• Daytime and evening phone numbers
• E-mail address
• Brief description of the problem and mail or ship to:
1100 Klein Road
Plano, Texas 75074
For technical assistance regarding your model, call 1-888-TRAXXAS
(872-9927), 972-265-8000 (outside of the U.S.), or e-mail Traxxas at
For orders and other information, call 972-265-8000.
Engine will not start
19 35
EZ-Start motor will not turn
EZ-Start turns but engine does not
Engine starts and then stalls
Engine sluggish, poor performance
15 21
30 29
Engine Overheats
34 31
Engine chokes/hesitates at speed
21 23
Engine stalls under hard acceleration
Engine stalls around turns
Engine stalls during normal driving 1
16 25
Out of fuel.......................................................................
Fuel level is low............................................................
Improper or contaminated fuel..............................
Excessive nitro in the fuel.........................................
Incorrect oil content in the fuel..............................
Poor quality fuel...........................................................
Engine not primed......................................................
EZ-Start battery not charged...................................
EZ-Start ground wire (yellow) faulty.....................
EZ-Start motor wire loose.........................................
One-way starter bearing slipping..........................
EZ-Start gears damaged............................................
Glow plug wire loose from glow plug.................
Glow plug wire damaged.........................................
Leaking glow plug gasket.........................................
Glow plug fouled or weak........................................
Engine flooded.............................................................
Engine overheated......................................................
Exhaust blocked...........................................................
Air cleaner plugged.....................................................
Carburetor incorrectly adjusted.............................
High-speed fuel mixture is too rich......................
High-speed fuel mixture is too lean.....................
Idle speed set too low................................................
Fuel flow blocked.........................................................
26 Air bubble in the fuel line.........................................
27 Insufficient fuel tank pressure.................................
Engine overheated......................................................
Engine overgeared for application.......................
Engine clutch slipping...............................................
Drive system is bound................................................
Engine excessively worn...........................................
Cooling air to the head is blocked........................
Excessive load on the engine..................................
Broken clutch shoe spring........................................
Loose flywheel..............................................................
EZ-Start motor pinion stripped..............................
Fill fuel tank
Refill fuel tank
Replace fuel
Use fuel with a lower nitro content (page 2)
Switch to a recommended brand of fuel (page 2)
Switch to a recommended brand of fuel (page 2)
Prime engine (page 6)
Use a freshly-charged battery (page 5)
Clean, tighten, or replace ground wire (page 12)
Check motor connections on the EZ-Start motor
Remove EZ-Start/ Clean or replace bearing (page 12)
Listen for excessive gear noise/ Replace gears/motor
Crimp the connector on the glow plug wire
Replace or repair glow plug wire
Check glow plug gasket/ tighten glow plug
Check for two solid green lights when the EZ-Start button is
pressed/ No GLOW PLUG light indicates a faulty plug/ Replace
with Traxxas 3230, 3231, or 3232 glow plugs (page 9)
Clear the engine of excess fuel (page 9)
Allow engine to cool- find cause for overheating
Clear any obstructions
Clean and replace air cleaner element (page 5)
Readjust carburetor to factory break-in settings (page 5)
Lean the high-speed mixture (page 7)
Richen the high-speed mixture (page 7)
Increase idle speed (page 7)
Check that all fuel lines are clear with no pin-hole leaks. Check
for dirt blockage in the carburetor fuel inlet and high-speed
needle seat/ Install inline fuel filter
Prime the engine to force the air through/ Check for pinhole
leaks in the fuel line
Replace the pressure hose (between pipe and fuel tank)/ clear
blockage in the tuned pipe hose fitting/ check flow to and from
tank/ Check fuel tank cap seal
Allow engine to cool/ find cause for overheating
Use a lower gear ratio (page 8)
Replace clutch shoes (see engine repair section, page 13)
Locate the bound item and repair
Repair or replace engine (page 12)
Cut ventilation holes in the body (windshield)
Check for bound drivetrain
Replace clutch shoe spring (page 13)
Replace flywheel nut (page 13)
Replace EZ-Start motor
STEP 12:
The piston and sleeve are a matched set. When the
piston and sleeve are disassembled, they must be
reassembled in the same orientation. Use a hobby
knife to scratch a mark to indicate the location of the
piston in relation to the pinning of the sleeve.
STEP 11:
Remove the backplate and the starter
shaft. Replace the backplate gasket
with a new one during assembly.
Use a 2.5mm hex driver to remove the three
remaining 3x10mm cap-head machine screws from
the engine mount.
Pull the engine from the chassis. Turn the engine so
that the throttle linkage to the carburetor will come out.
STEP 10:
Use a 2.5mm allen wrench to remove the four 3x12mm
cap-head screws that fasten the cylinder head. Rock
the cylinder head gently from side to side to release it
from the sleeve. Note the thin aluminum head gaskets.
We recommend that you replace these gaskets with
new ones upon reassembly.
STEP 9: Changing the piston and sleeve
Use a 5/16 inch nut driver to remove the glow plug and
copper gasket.
Removing the carburetor is not necessary to rebuild
the engine, unless you intend to replace the internal
bearings of the engine. Remove the carburetor by
loosening the 3mm locknut and pulling the carburetor
straight up.
Remove the 3x23mm cap-head machine
screws that fasten the header to the
engine. Carefully remove the header to
avoid damaging the gasket.
To separate the engine from the engine
mount, remove the four 3x8mm cap-head
machine screws.
Use a 2.5mm hex driver to remove the yellow ground
wire from the engine mount. Move the EZ-Start wiring
harness out of the way.
Remove the EZ-Start gearbox by removing the three
3x8mm round-head machine screws.
Unplug the blue wire from the glow plug. Remove the
fuel line from the carburetor inlet and from the exhaust
header pressure fitting. Disconnect the red and black
wires from the EZ-Start® motor.
Remove the 4mm locknut from the front
pipe hanger. Pull the pipe from the rear
exhaust header.
Rebuilding the Engine
STEP 18:
Remove the clutch bell gear and the clutch shoes.
Note that there are two 5x8mm Teflon® washers, one
on each side of the clutch bell gear. Check the clutch
shoes for excessive wear
or cracking around the pin
holes. If the clutch shoes
are worn to the point that
the clutch spring contacts
the clutch bell, then the
shoes must be replaced.
STEP 17: Removing the clutch and flywheel
It is not necessary to remove the clutch assembly
unless you are servicing the clutch, crankshaft, or
engine bearings. Use the tip of a small screwdriver to
remove the E-clip which holds the clutch bell gear.
STEP 16:
To remove the connecting rod from the piston, use a
sharp-pointed tool to remove the small metal G-clip
in the side of the piston. Do not re-use the old Gclip. When installing a new connecting rod, use the
supplied new G-clip.
STEP 15:
Remove the connecting rod and piston through the top
of the crankcase.
STEP 14:
Rotate the crankshaft to bottom dead center. Lightly
grab the connecting rod with a pair of needlenose
pliers and gently pull it off of the crankshaft journal.
STEP 13:
Pull the sleeve straight up and out of the crankcase. If
the sleeve will not move, rotate the crankshaft until the
sleeve pushes up.
STEP 24:
Use the 1200 grit sandpaper and the liquid metal
polish on the wrist pin also. Rinse thoroughly with
denatured alcohol and lube with after-run oil.
STEP 23:
Before installing a new connecting rod, you can
increase connecting rod life by polishing the crankshaft
journal. Use 1200 grit sandpaper to remove the
surface scratches followed by liquid metal polish to
buff the crankshaft journal to a bright, smooth shine.
Rinse thoroughly with denatured alcohol. Lube with
after-run oil.
STEP 22:
The bearings are press-fit into the crankcase. To
remove them, the crankcase must be heated with a
heat gun or torch. The crankcase will expand with
heat and release the bearings. To avoid the possibility
of burns or other damage, do not attempt remove the
bearings. Clean the bearings by flushing them with
denatured alcohol and then place one or two drops of
after-run oil on the races.
STEP 21:
Remove the crankshaft by pulling it straight out of
the crankcase.
STEP 20:
The flywheel and the split-beveled cone should pull
smoothly off of the crankshaft.
STEP 19:
Grip the flywheel with a
pair of pliers (locking pliers
work best). Remove the
clutch adapter nut with a
10mm deep socket. Hold
the engine just above your
workbench and tap the
flywheel from behind with a
non-marring hammer (plastic or wood). Several easy
blows may be necessary to release the flywheel and
split beveled cone.
STEP 33:
Turn the gear over and install the other ball bearing.
STEP 27:
Place another drop of oil on the connecting rod
bushing. Rotate the crankshaft several times to
distribute the oil.
STEP 30:
Reinstall the starter shaft. Align the notch in the starter
shaft with the crankshaft journal pin (arrow).
STEP 29:
Install new head gaskets on the head. Use one
thick and one thin gasket. Reinstall the head using
the 3x12mm cap-head machine screws. Tighten the
screws in small increments, in a criss-cross pattern,
until all the screws are tight.
STEP 28:
Insert the sleeve into the top of the crankcase. Rotate
the sleeve so that the notch in the sleeve will line
up with the pin in the crankcase. Holding the engine
upside down will make it easier for the sleeve to go
over the piston.
STEP 32:
Install the appropriate size ball bearing into one side
of the clutch bell gear. The Nitro Stampede comes
stock with an 18-tooth clutch bell gear which requires
5x11mm ball bearings.
STEP 26:
Reinstall the crankshaft into the engine and make
sure that it spins freely. Insert the connecting rod and
piston assembly through the top of the crankcase. The
G-clip should face the carburetor. Put a drop of castor
or after-run oil in the bottom end of the connecting
rod. Use your fingers to gently push the end of the
connecting rod over the crankshaft journal.
STEP 36:
Reinstall the carburetor with a new O-ring, header,
a NEW glow plug, and engine mount. Use a new
header gasket when re-installing the header on
the engine. Reinstall the engine in the truck in the
reverse order of removal. Don’t forget to reconnect
the yellow grounding wire to the engine mount. The
rebuilt engine must now be broken in.
STEP 35:
Install the clutch shoes
exactly as shown in the
drawing (leading edge
engagement). Next, install
a 5x8mm Teflon® washer
followed by the clutch
bell gear (with bearings
installed). Install the
remaining 5x8mm Teflon®
washer followed by the Eclip (see step 14).
STEP 34:
Install the split-beveled cone onto the crankshaft.
Next, install the flywheel. Install the clutch adapter
nut with a 10mm deep
socket. Grip the flywheel
with pliers while tightening
the adapter nut.
STEP 31:
Reinstall the backplate and a new backplate gasket
with the 3x8mm cap-head machine screws. Tighten
the screws in small increments, in a criss-cross pattern
until all the screws are tight.
STEP 25:
To assemble the connecting rod and piston, place a
drop of castor oil in the top end of the connecting rod.
Insert the wrist pin through the piston and the top of
the connecting rod. Secure the wrist pin with the Gclip. Make sure the G-clip fits securely into the groove
machined in the piston. Be careful not to scratch the
sides of the piston.
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