Zenoah G300PUM Owner's Manual page 10

8. Carburetor Adjustment
Idle Screw:
Turning this screw clockwise increases the idling R.P.M. Turning it
counterclockwise decreases the idling R.P.M
Low Speed needle:
This is the fuel adjust screw (not the air screw). Turning this needle clockwise
makes the mixture gas leaner and turning it counterclockwise makes it richer.
Set this needle at a position which is 1/4 open from best mixture (maximum
R.P.M.) position.
High Speed needle:
Turning this needle clockwise makes the mixture gas leaner and turning it
counterclockwise richer. Set this needle at a position which is 1/8~1/4 open
(counter clockwise) from the maximum R.P.M. position.
CAUTION
1. Do not tighten the High and Low Speed needles too firmly.
2. When the unit has just started and the engine is not warm enough, there
may be insufficient acceleration and the engine may be stopped. Be sure
to perform idling before operation.
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