PERIODIC MAINTENANCE AND MINOR REPAIR
6-12
6
EAU21290
Adjusting the carburetors
The carburetors are important parts of
the engine and require very sophisticat-
ed adjustment. Therefore, most carbu-
retor adjustments should be left to a
Yamaha dealer, who has the neces-
sary professional knowledge and expe-
rience. The adjustment described in the
following section, however, may be ser-
viced by the owner as part of routine
maintenance.
CAUTION:
ECA10560
The carburetors have been set and
extensively tested at the Yamaha
factory. Changing these settings
without sufficient technical knowl-
edge may result in poor perfor-
mance of or damage to the engine.
EAU21340
Adjusting the engine idling
speed
The engine idling speed must be
checked and, if necessary, adjusted as
follows at the intervals specified in the
periodic maintenance and lubrication
chart.
The engine should be warm before
making this adjustment.
NOTE:
●
The engine is warm when it quickly
responds to the throttle.
●
A diagnostic tachometer is needed
to make this adjustment.
1. Attach the tachometer to the spark
plug lead.
2. Check the engine idling speed
and, if necessary, adjust it to spec-
ification by turning the throttle stop
screw. To increase the engine
idling speed, turn the screw in di-
rection (a). To decrease the en-
gine idling speed, turn the screw in
direction (b).
NOTE:
If the specified idling speed cannot be
obtained as described above, have a
Yamaha dealer make the adjustment.
1. Throttle stop screw
Engine idling speed:
950–1050 r/min
5YS20.book Page 12 Thursday, June 19, 2003 1:41 PM
