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8-15
EBU00296
Carburetor adjustment
The carburetor is a vital part of the engine and
requires very sophisticated adjustment. Most
adjusting should be left to a Yamaha dealer
who has the professional knowledge and ex-
perience to do so. However, the idling speed
may be performed by the owner as a part of
the usual maintenance routine.
CAUTION:
The carburetor was set at the Yamaha fac-
tory after many tests. If the settings are
disturbed by someone without sufficient
technical knowledge, poor engine perfor-
mance and damage may result.
EBU00301
Idle speed adjustment
N
O
TE:
A diagnostic tachometer must be used for this
procedure.
1. Start the engine and warm it up for a few
minutes at approximately 1,000 to 2,000
r/min. Occasionally rev the engine to
4,000 to 5,000 r/min. The engine is warm
when it quickly responds to the throttle.
2. Connect the tachometer and set the idle
to the specified idling speed by adjusting
the throttle stop screw. Turn the screw in
to increase engine speed, and out to de-
crease engine speed.
Specified idle speed:
1,400–1,500 r/min
U4XE15.book Page 15 Monday, April 8, 2002 2:19 PM