GAS GAS EC 125 - 2003 Service Manual page 41

Slow Jet (piltot jet) and air screw
The slow jet and air srew controls the mixture in the closed to 1/8
throttle range, but has little effect on up to full throttle. To adjust the
mixture in this range, the air screw can be turned to change the air
flow through the circuit, or the slow jet can be changed to provide
more or less fuel. Start by turning the air screw to provide more or
less fuel. Screwing it in richens the mixture. Air screw (A) specs
indicate the turns out from a lightly seated position. Make changes
in 1/2 turn increments. If turning the srew between one and two-
and-a-half turns doesn´t provide the desired results, change the
slow jet (B).
Jet needle
The jet needle and jet needle hole together have their greatest effect
in the 1/4 to 3/4 throttle range. The needle moves in and out of the
jet needle hole; since the needle is tapered, its position in the jet
determines the amount of fuel allowed through. There are five
grooves in the top of the needle in which a circlip fits. This clip
locates the needle in the throttle valve and, therefore, determines
its position relative to the jet needle hole.
Test runs
- Warm up the engine with the carburetor at the standard settings,
and run two or three laps of the course while examining the operating
condition of the spark plug.
- Test-ride the bike by varying the throttle opening.
Symptoms of improper settings
If your machine exhibits one or more of the symptoms listed below,
it may need carb tuning changes.
Before attempting any changes, however, make sure that everything
(B)
else is in good shape and tuned properly.
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EC 2003 - -
Clip position
Needle size
number
Working area