20
MAN-028
5- CARBURETOR ADJUSTMENT GUIDE
1 T.O.
*
RICH LEAN
1 ¼ T.O. ¾ T.O.
1 ½ T.O.
*
T.O. = TURNS OPEN
The carburetors are originally supplied with a fixed jet on the High speed.
The screws L and I are pre-set to start and run the engine.
L: 1 ¼ T.O. for the 62cc engine and 1 ½ T.O. for the 100 and 125cc engines (unscrew
counterclockwise from completely screwed in).
I: 1 ÷ 2 T.O. (screw in clockwise after contact with throttle lever).
The adjustment is optimized for hot engine.
ATTENTION:
Never set the mixture screw L under 1 ¼ T.O. for the 62cc engine. As the 100
and 125cc engines are concerned the carburetors (HL 384A and B) are supplied
with an internal bypass on the L screw that guarantees a suitable flow even
when L is completely closed.
However do not set the L screw under 1 ½ T.O.
If the mixture is too lean, the engine will overheat and result in seizure.
Start the engine. If the idle RPM is too high adjust (I) counterclockwise to reduce RPM
until the clutch is disengaged.
Allow engine to heat up for 2-3 minutes.
Accelerate engine, if acceleration is bad then the low speed mixture screw (L) is either
set too lean or too rich.
1- Adjust (L) 1/8 turn counter clockwise, reset (I) and accelerate
If acceleration improves but not enough then repeat step 1 until acceleration is
satisfactory
If acceleration disimproves then return to original setting and proceed to step 2
2- Adjust (L) 1/8 turn clockwise, reset (I) and accelerate
If acceleration improves but not enough then repeat step 2 until acceleration is
satisfactory
The idle system is now at its optimum setting whch should mean a stable idle and
good acceleration
Accelerate the engine to wide open throttle (W.O.T.) if maximum RPM attained is too
high or too low then a change of high speed jet is required (see procedure for jet
change). If RPM too high then a larger jet is required and if RPM too low a smaller jet
is required.
LOW SPEED MIXTURE SCREW ( L)
( I ) IDLE SPEED
REGULATION SCREW
FIXED HIGH SPEED JET
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