Yamaha TTR90(M), Owner'S Service Manual

Page: 124 / 287

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INSP
ADJ
IDLE SPEED ADJUSTMENT/
VALVE CLEARANCE ADJUSTMENT
EC35M021
IDLE SPEED ADJUSTMENT
1. Start the engine and thoroughly warm it
up.
2. Adjust:
●
Idle speed
Adjustment steps:
●
Adjust the pilot screw.
Refer to “PILOT AIR SCREW ADJUST-
MENT” section.
●
Turn the throttle stop screw 1 until the
engine runs at the lowest possible speed.
To increase idle speed
→
Turn the throttle stop screw 1 in
a
.
To decrease idle speed
→
Turn the throttle stop screw 1 out
b
.
Engine idling speed:
1,450 ~ 1,550 r/min
VALVE CLEARANCE ADJUSTMENT
NOTE:
●
The valve clearance should be adjusted
when the engine is cool to the touch.
●
The piston must be at Top Dead Center
(T.D.C.) on compression stroke to check or
adjust the valve clearance.
1. Remove:
●
Air scoop (right) 1
●
Air filter case 2
2. Remove:
●
Tappet cover (intake side) 1
●
Tappet cover (exhaust side) 2
3. Remove:
●
Timing plug 1
●
Straight plug 2
●
O-rings