GAS GAS SM 2008, User Manual

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Idling nozzle and mixture adjustment screw
Controls the mixture from the closed position to an opening of 1/8
of throttle range, but has little effect on 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. Screwing it in richens
the mixture. The air screw must be turned from a lightly seated
position. Make changes in 1/2 turn increments. If turning the screw
between 1 and 2.5 turns does not give the desired results, change
the slow jet
(B) one step and tune up with the air screw (A) .
Carburetor jet needle
The jet needle and jet needle hole together have their greatest effect
in the one-half 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 to flow.
There are five grooves in the upper section of the needle where a
circlip fits. This clip locates the needle in the throttle valve and
determines its relative position in the jet needle hole, and provides
a rich mixture. Moving the clip to the top will provide a lean mixture.
Change the clip position one step at a time. The straight area of the
needle affects throttle valve response in the small openings range.
Test runs with the motorcycle
- Warm up the engine with the carburetor at the standard setting,
and inspect the operating conditions of the spark plug.
- Test-ride the motorcycle with the throttle opened.
Symptoms of improper settings
If your motorcycle exhibits one of the following symptoms the changes
must be adjusted. Before attempting any changes, make sure that
everything else is in good operating condition.
(B)
Clip position
Jet needle
number
Right section
(A)