Suzuki RM125 Owner's Service Manual page 52

JUDGING AIR/FUEL MIXTURE
For proper carburetor tuning, it is necessary to
know how to judge the air/fuel mixture made in the
carburetor; whether too rich, too lean or properly
mixed. Given below are the symptoms observed
when the engine is not supplied with the proper
air/fuel mixture ratio from the carburetor. Check
each item as reference for judging the air/fuel mix-
ture condition.
When air/fuel mixture is too rich
1) The engine noise is dull and intermittent.
2) The engine condition becomes worse when the
bypass is applied.
3) The engine condition becomes worse as it is
warmed up.
4) The engine condition improves when the air
cleaner is removed.
5) The spark plug is fouled with carbon (wet and
oily).
6) The exhaust gas produces heavy smoke.
When air/fuel mixture is too lean
1) The engine overheats.
2) The engine condition improves when the
bypass is applied.
3) Acceleration is poor.
4) The spark plug is burned white.
5) The speed of the engine fluctuates and lack of
power is noticed.
6) Detonation and pinging are experienced.
TUNING PROCEDURE
The following indicates the correct tuning procedure
for this motorcycle. Understand the procedure by
first riding the motorcycle where it will be used and
adjust the engine to the best condition after judging
the air/fuel mixture.
Carburetor standard setting
Main jet: #370
Jet needle: 6CHY17-65-3rd
Pilot jet: #42.5
Air screw: 2 turns out
INCLUDED PARTS AND OPTIONAL PARTS
Main jet
Air/fuel
SIZE
mixture
Lean #300
#310
#320
#330
#340
#350
* #360
#370
* #380
* #390
#400
#410
#420
#430
#440
#450
#460
#470
#480
#490
Rich #500
Pilot jet
Air/fuel
SIZE
mixture
Lean #25
#27.5
#30
#32.5
#35
#37.5
#40
#42.5
#45
#47.5
Rich #50
MACHINE TUNING 4-7
P/NO
09491-60007
09491-62005
09491-64002
09491-66002
09491-68002
09491-70011
09491-72011
09491-74003
09491-76003
09491-78005
09491-80010
09491-82007
09491-84008
09491-86002
09491-88001
09491-90005
09491-92002
09491-94004
09491-96001
09491-98001
09491-10001
P/NO
09492-25011
09492-27011
09492-30014
09492-32010
09492-35021
09492-37003
09492-40028
09492-42023
09492-45034
09492-47022
09492-50024