Suzuki RM-Z250 - Front Fork Tuning

4-8 MACHINE TUNING
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
choke 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).
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 choke
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: #170
Jet needle: NLCT-4th
Slow jet: #45
Pilot screw: 1 and 1/2 turns back
INCLUDED PARTS AND OPTIONAL PARTS
Main jet
Slow jet
Air/fuel
mixture
SIZE P/NO.
Lean #150 09491-30018
#152 09491-30019
#155 09491-31012
#158 09491-31013
#160 09491-32010
#162 09491-32011
* #165 09491-33009
#168 09491-33010
#170 09491-34010
#172 09491-34011
* #175 09491-35009
#178 09491-35010
#180 09491-36008
#185 09491-37008
Rich #190 09491-38011
Air/fuel
mixture
SIZE P/NO.
Lean #35 09492-35019
#40 09492-40022
#42 09492-42019
#45 09492-45032
#48 09492-48013
#50 09492-50023
#52 09492-52011
#55 09492-55017
#58 09492-58001
Rich #60 09492-60016