5- CARBURETOR ADJUSTMENT GUIDE
1 T.O.
*
RICH LEAN
1 ¼ T.O. ¾ T.O.
1 ½ T.O.
*
T.O. = TURNS OPEN
Normally the correct setting of the mixture screws is the following:
?? L (close the screw completely and then open): 1 ¼ ÷ 1 ½ T.O.
?? H (close the screw completely and then open): 1 ÷ 1 ¼ T.O.
Based on various factors as altitude, ambient temperature etc. it might be necessary to reset the carburetor to optimize
the performance of the engine.
ATTENTION:
- Never lean too much as lean mixture will overheat engine and cause seizure
- Do not force H or L closed. It may damage the precision machined orifice and render the carb unserviceable.
- The adjustment of screw must be performed with warm engine.
(H)
Adjust T.O. from closed to
approximately:
1 ¼ .T.O.
(L)
Adjust T.O. from closed to
approximately 1 ¼ T.O
(I)
Close by further 1 ½ T.O.
after contact with throttle
lever.
Start the engine and warm it. If R.P.M. too
high adjust I counterclockwise until clutch is
disengaged.
Turn c.c.w. until max.
R.P.M. is reached. Adjust
further fractionally for rich
idle.
Trigger accelerator.
If R.P.M
decreases
(L)
Slowly adjust clockwise
If R.P.M.
increases
Continue to turn clockwise
until max. R.P.M. is reached
.Adjust c.c.w. fractionally for
rich idle.
Trigger accelerator.
Engine is now idling at max. attainable
R.P.M. or slightly lower on rich side.
Adjust I counterclockwise until 2000 ÷ 2500
R.P.M. is reached
Recheck L screw for optimum setting
required.
Adjust H until best possible free speed is
reached. Turn clockwise for higher R.P.M.
Counterclockwise for lower R.P.M.
Adjust L slightly richer by
1/8 ÷ ¼ T.O.
Bad
acceleration
Return to idle and check acceleration for
quick response and smooth pick-up.
Good
acceleration
Engine ready to operate.
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