32
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T-MAXX 2.5R
When adjusting the low
speed fuel mixture, it is
very important to make
several high-speed runs
with T-Maxx 2.5R 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 22
for more information
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.
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 (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 T-Maxx 2.5R from doing a wheelie when you accelerate!
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 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.
The TRX 2.5R Racing Engine
is..
Lower
Higher
Lower
Higher
Lower
Higher
Lower
Higher
Lower
Higher
then the air density is...
Slightly more dense
Slightly less dense
Less dense
More dense
More dense
Less dense
More dense
Less dense
adjust (correct) the
fuel mixture to be...
Slightly richer
Slightly leaner
Leaner
Richer
Richer
Leaner
Richer
Leaner
Leaner
Richer
If the...
Humidity
Pressure (barometer)
Temperature
Altitude
Nitro %
Fuel Mixture Adjustment Chart
Summary of Contents for 4902
Page 1: ...MODEL 4902 owners manual ...
Page 46: ......
Page 47: ......
Page 48: ...1 100 Klein Road Plano Texas 75074 1 888 TRAXXAS MODEL 4902 owners manual 060215 Part 5197 ...