4-6 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
starter 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 starter
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: #128
Jet needle: 24NAAH-3rd
Slow jet: #50
Air screw: 2 turns out
INCLUDED PARTS AND OPTIONAL PARTS
Main jet
Slow jet
Jet Needle
NOTE:
SHADED : STANDARD
* : INCLUDED PARTS
NONE : OPTIONAL PARTS
Air/fuel
mixture
SIZE P/NO
Lean #115 09491-23027
#118 09491-23028
#120 09491-24030
* #122 09491-24031
#125 09491-25019
#128 09491-25020
* #130 09491-26017
#132 09491-26018
* #135 09491-27016
#138 09491-27017
#140 09491-28019
#142 09491-28020
Rich #145 09491-29014
Air/fuel
mixture
SIZE P/NO
Lean #45 09492-45032
#48 09492-48013
#50 09492-50023
#52 09492-52011
#55 09492-55017
Rich #58 09492-58001
Air/fuel
mixture
SIZE P/NO
Lean 24NCDK 13383-03B90
24NAAK 13383-03B40
24NCDJ 13383-03B80
24NAAJ 13383-03B30
24NCDH 13383-03B70
24NAAH 13383-03B20
24NCDG 13383-03B60
24NAAG 13383-03B10
24NCDF 13383-03B50
Rich 24NAAF 13383-03B00
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