MACHINE TUNING 4-7
1 Adjustment of slow system
1) Set the air screw as specified.
2) See if the selected slow jet is correct or not by
judging the air/fuel mixture. If air/fuel mixture is
rich, replace it with smaller one. If air/fuel mix-
ture is lean, replace it with larger one.
2 Adjustment of main system
With the throttle opened 3/4 to full, make main sys-
tem adjustment monitoring the air/fuel mixture con-
dition after completion of pilot system settings.
* If selection of the main jet is between the col-
umns, take the larger number main jet first to pre-
vent the piston seizure.
* Make sure to adjust the main system before
adjusting the intermediate system.
3 Adjustment of intermediate system
Monitor the air/fuel mixture condition and adjust the
intermediate system by selecting the proper needle
size. Changing standard needle within one size
(larger or smaller) will cover almost any race condi-
tion.
4 Fine adjustment of slow system
After a proper standard setting has been obtained
by the procedure 1 through 3, fine tune the carbu-
retor according to the actual race conditions.
1) Adjust the air/fuel mixture by tuning the air
screw within 1/2 – 2 turns out.
1/2 turn out
1 – 1/2 turns out
2 turns out
2) If the mixture can not be adjusted by the air
screw within 1/2 – 2 and 1/4 turns out range,
readjust the pilot system 3.
5 Fine adjustment of intermediate system
Fine tune the intermediate system by changing the
clip position.
Ex. Pilot jet #50
If air/fuel mixture is rich, replace it with #48
slow jet. If air/fuel mixture is lean, replace
it with #52 slow jet.
Ex. Main jet #128
If air/fuel mixture is rich, replace it with
#125 main jet. If air/fuel mixture is lean,
replace it with #130 main jet.
Lean
STD
Rich
1
2
3
4
5
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