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CARBURETOR ADJUSTMENT – AT THE TRACK
You can only fine-tune the main needle setting at the track. Initially, the main needle should still be set a little rich. Fill the fuel
tank, run the car up to maximum speed for a few laps, and check if it reaches top RPM without running rich towards the end
(4-stroking). Lean the main needle by small increments (1/12 of a turn, like 1 hour on a clock) and run the car again. Repeat
these small adjustments until the engine accelerates well and reaches maximum speed without running rich. It is advised to
then richen the main needle 1/8 of a turn (counter-clockwise).
Running the engine too lean will cause the engine to overheat, resulting in excessive engine wear and possibly breakdown.
A fast, simple way to check the engine temperature is to apply a few drops of water to the cylinder head. The drops should
evaporate only after 3-5 seconds. If they evaporate immediately the engine is too hot; richen the main needle 1/8 of a turn
(counter-clockwise). Check engine temperature regularly and often.
The idle RPM and low-speed needle settings may require a little fine tuning after the main needle has been set properly. Once
properly adjusted, the engine should produce a strong, high-pitched sound at maximum speed, and a thin trail of smoke
should be visible from the exhaust tailpipe.
For more information about setting the idle and low-speed needle settings, see section Carburetor Adjustment – Before
Putting the Car on the Track.
NOTE:
The carburetor settings may change with changes in weather conditions, fuel, glowplug, or exhaust system. After
changing any of these, always richen the main needle (counter-clockwise) ¼ to ½-turn and then re-adjust the main needle
again on the track.
Summary of Contents for NT18 0.8cc
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