OWNERS MANUAL
160 ULTIMATE KIT
V2014/1
Part Nr.: 12103-K26-590AU
INTRODUCTION
Thank you, and congratulations on your purchase of the all-new YUMINASHI 160
Ultimate Light Bore kit for the Honda Grom/MSX125.
This manual will provide you with some background information, instructions on how
to install the kit, and explain how to achieve the best performance from our new
Grom/MSX 160 Ultimate Kit.
Please read this manual very carefully before use!...
RECOMMEND OCTANE RATINGS
Recommend octane rating for Japan Europe - Australia & Thailand
91 - 95 OCTANE
Recommend octane rating for the U.S.A. & Canada
87 - 91 OCTANE (Regular - Premium)
**Please note: If you use a much higher octane ratio than recommended your engine
may not perform optimally. This is due to slower flame propagation. Ensure you are
using 87 octane in the US/Canada, or 91 octane in other countries and that it is a
good quality fuel. If your hear a knocking noise coming from the engine try a fuel with
a slightly higher octane rating!...
1.
EXHAUST!
Ensure when you install your new Yuminashi 160 Ultimate Kit, the
outside diameter of your header isn't larger than 1 inch (25.4mm).
Optimal inside diameter is between 21.5 – 21.8mm (0846 – 0.858
inch).
If the exhaust header diameter is larger
than 1 inch you will not get full power
output from the 160cc kit and will
result in a loss of top speed and
reduced acceleration characteristics.
If you have an IXIL exhaust, you
certainly need to check the inner
diameter of your header at the
cylinder head side.
During testing IXIL exhaust systems with the correct outside diameter of 1 inch, but
with a very thick weld on the inside diameter which caused the opening to be too small
for the 160cc kit.
We recommend removing the excess material inside the header in order to achieve
the recommended inside diameter of (.846 to .858 inch).
REINFORCED CLUTCH SPRINGS (6Pcs/Set)
Your 160 Ultimate set includes reinforced clutch springs
meant to replace the 6 stock Honda springs in order to
prevent clutch slippage caused by increased HP and torque.
The reinforced clutch spring rates were carefully chosen
with daily driving in mind to provide enough pressure to
avoid clutch slippage, but not so stiff stiff as to cause hand fatigue.
** The springs come in 2 colors.
The 3 blue springs are stiffer and the red lighter. If clutch feel is too stiff when
installed together simply remove the red and replace them with the stock springs.
Keep in mind that the the blue springs need to be installed on the 3 bolts from the
clutch.
2.
The 4th gear and final-drive sprocket combination
plays a very crucial role in the performance outcome
of your new 160 Ultimate Light Bore kit.
RECOMMENDED SPROCKET SETUP
This kit has been optimized for a 15/34T sprocket combination with the stock 4th
gear 26/24 (0.92 ratio).
With the ECU in “RPM limited touring mode” (please check page 5. for the ECU
modes) Speeds of up to 130Km/h (80.78Mph) may be attained under perfect road
and weather conditions without any head wind.
Top speed is based upon a rider weighing 80Kg (176.4) or less. Your top speed will
vary based upon rider’s weight and proper exhaust header diameter.
If your weight exceeds 80Kg (176.4 Pounds) a sprocket combination of 14/32T as a
mid-point may produce more desirable acceleration characteristics. Another option
is a 34T or 35T rear if more torque and acceleration is desired. We don’t
recommend using 14T front sprocket in combination with your stock 34T rear
sprocket if you want to be able to reach a top speed of 130Km/h (80.78Mph).
Ultimately the sprocket combination one chooses will be a matter of personal taste.
Keep in mind that as soon as you are changing the stock gear sprockets, or finaldrive sprockets, your genuine MSX/GROM125 speedometer won’t be able
anymore to show you the accurate speed!
-Changing the 4th gear sprocket combination will give you a very pleasant
and much longer first, second and thirth gear where you make it your
engine a lot easier to gain top speed each and every time, and this in both,
the limited RPM Touring mode and in the open RPM Racing mode.
**Use the table on the next page as a comparison in top speed (in Touring mode) in
order to assist you in choosing which front and rear sprocket combination will work
best for you.
3.
4.
2,5
2,5
YUMINASHI
23471-K26SPORTS
025B
GEAR
TAKEGAWA
CROSS 02-04-0292
MISSION
2,5
2,5
STOCK
HONDA
LARGE
OVERDRIVE
RATIO
GEAR 1
YUMINASHI
23471-K26SHORT
025
OVERDRIVE
PART
NUMBER
GEAR SET
BRAND &
GEAR SET
NAME
RATIO
GEAR 4
56,96Km/h
87,29Km/h
116,04Km/h
131,46Km/h
1,63
1,23
1,083
35,39Mph
54,24Mph
72,11Mph
81,69Mph
52,04Km/h
83,93Km/h
113,12Km/h
130,09Km/h
1,55
1,15
1,00
32,34Mph
52,15Mph
70,29Mph
80,84Mph
50,26Km/h
81,07Km/h
109,27Km/h
130,89Km/h
1,55
1,15
0,96
31,23Mph
50,38Mph
67,90Mph
81,34Mph
17
16
15
15
33
34
33
34
WITH
WITH
TOP SPEED G4
RECOMMEND RECOMMEND
TOURING
FRONT
REAR
MODE
SPROCKET
SPROCKET
48,78Km/h
78,69Km/h
106,05Km/h
132,13Km/h
1,55
1,15
0,92
30,31Mph
48,90Mph
65,90Mph
82,11Mph
TOP SPEED G1
TOP SPEED G2
TOP SPEED G3
RATIO
RATIO
TOURING
TOURING
TOURING
GEAR 2
GEAR 3
MODE
MODE
MODE
** Results may vary depending upon tire circumference
YUMINASHI
YUMINASHI 160
160 ULTIMATE
ULTIMATE -- SPROCKET
SPROCKET &
& GEAR
GEAR TABLE
TABLE
STAND-ALONE DUAL MAP ECU UNIT
(PROGRAMMABLE) WITH OVERHEATING CONTROL
Yuminashi R&D began from scratch with our Ultimate Light
Bore series kit. The goals were to offer an entirely blue
printed cylinder kit, to be able to increase the power of the
kit, and to simplify tuning by eliminating guess work.
The ECU, camshaft, valves, springs, injector and all other
parts have been optimized to work together as one set. As a result it eliminates the
need for the customer to figure our ignition timing and AFR ratios by themselves. The
result is the risk of engine damage caused by improper setup or incompatible parts is
greatly reduced
Yuminashi takes durability and reliability very serious, and that’s the reason why we as
first company in the world include a standalone ECU system with overheat protection
built in. We did this to protect your investment and to provide our customers with
satisfying results in regards to performance.
The benefit of our new stand-alone ECU system is not only to be able to control the
fueling accurately, but to eliminate conflicts with the stock ECU like have been seen in
the past with some piggy back systems where engine damage could be the result.
The Overheating Control feature built in to our stand-alone ECU system monitors your
engine temperature under all conditions. This system in your ECU is programmed to
“give your engine a break” when it is being over stressed by reducing the ignition
timing and by adjusting the Air Fuel Ratio. This is done to avoid engine damage, even if
you are an extremely aggressive rider and are in Racing mode.
If your engine begins to run hot, the rider will feel it because your engine will
temporarily have less power. The ECU has been programmed this way, but will return
to normal once soon as the engine temperature has come down. If this occurs often,
we recommend installation of an oil cooler. This is a great feature for anyone living in
areas that have hot climates.
Installing our Stand-alone ECU system is very easy and is simply
plug&play. Just remove the stock unit and plug the new ECU into
the harness. The new ECU is programmed and optimized to be
used in combination with the 8-hole Big Bore fuel injector that
comes included with the kit.
5.
Our stand-alone ECU is a dual-mode system which gives the rider the ability to choose
between two different modes/maps.
Mode #1: Touring mode
This mode is the most economical mode and may be used for “daily driving”. In this
mode engine RPM is limited to 10,500 RPM. This is the default mode which the unit will
be in from the factory.
Mode #2: Racing mode
Racing mode increases the engine RPM limiter to 12,000RPM. In order to switch to
Racing mode the included jumper plug needs to be installed.
**Both modes can be separately adjusted or programmed by your official Yuminashi
dealer.
8-HOLES BIG BORE INJECTOR
The 8-Hole Big Bore injector included in the kit has been matched
to provide the optimal flow rate for use with the 160cc cylinder kit
and has proven to be the perfect match in conjunction with the
stock Honda Grom/MSX125 throttle body.
The benefit of this larger flow injector is it allows us to maintain a duty cycle that
does not push the limits of the stock 125cc injector. This ensures that throughout the
RPM range the AF ratio never leans out and causes engine damage. It promotes
better fuel atomization, results in smoother throttle response and better overall
performance.
Because everything has been optimized for the stock head it is not necessary to
modify the port diameter on the intake runner or exhaust manifold side. If they are
modified reduced performance will result due to decreased gas velocities.
The injector and ECU are blue printed to be used in combination with the stock
GROM/MSX125 air filter. If you are using the stock air filter we advise removing the
small metal bracket inside the air filter box and removing the restrictor tube inside
the stock air filter.
6.
SX290 8.2 HIGH-LIFT CAMSHAFT
NEW HIGH-LIFT VALVES
PROGRESSIVE DOUBLE
VALVE SPRINGS
Yuminashi R&D has developed the all new SX290 8.2 high-lift camshaft to be used in
conjunction with the 160 Ultimate kit. In order to achieve the best performance possible
with your stock ports, manifold and throttle body, we have not only increased the valve
timing duration, but also the lift. This makes Yuminashi camshaft the first in the world
with a lift of 8.2mm (0.3228 inch).
** Measurements are referring to the intake valve lift, not the intake valve lobe height of
the camshaft.
In order to make such high lift possible with the stock 125cc head without causing the
valve retainers to hit the valve guides and seals new valves had to be developed as well
which are included in the 160cc Ultimate kit.
Warning: Never install the SX290 8.2 camshaft with the stock Honda valves.
These valve train components are designed to work together and therefore
should not be used separately.
Valve clearance must be set to .05mm intake and .08mm exhaust.
The double progressive valve springs should be installed to prevent valve float in Racing
mode.
7.
ENGINE RUNNING ON IDLE
Upon starting your Grom/MSX125 for
the first time after installation of the
160 Ultimate Kit there is a good
likelihood the engine will idle either too
high or too low. From the factory the
idle air screw has been adjusted for the
125cc engine and not 160cc with a high
lift cam.
Setting the idle speed is simple. In the
picture the location of the Idle air
screw is indicated.
Turning the screw clockwise will cause the engine to run richer (reduced airflow).
Turning the screw counterclockwise will cause the engine to run leaner (increased
airflow). Adjust the screw until the desired Idle is achieved (~1600RPM).
The picture is of a European model MSX125 which has an Intake Air Control Valve (IACV).
The Thai MSX125, Japanese and US Grom models will not have an IACV, however the
idle air screw is located in the same position and operates in the same fashion.
If this instruction pamphlet has been read you should have enough information to
install the kit. If additional assistance is required please contact your official Yuminashi
dealer.
If you would like to see step by step installation steps for a big bore kit installation, then
we recommend you to take a visit at www.inveniamperformance.com
Thank you for purchasing this Yuminashi product. We wish you a lot of fun with your
new 160 Ultimate Set!
WWW.YUMINASHI.COM
8.
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