Yamaha YZ 2019 Series, Owner'S Service Manual

Page: 104 / 398

ENGINE
3-16
TIP
Get the high tension cord “1” of the ignition coil
pinched in the detector “a” of the digital tachom-
eter.
4. Measure:
• Engine idling speed
Out of specification

Regulate.
5. Adjust:
•
Engine idling speed
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a. Turn the starter knob/idle screw “1” in the di-
rection of “a” or “b” to make an adjustment.
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EAM30226
ADJUSTING THE VALVE CLEARANCE
TIP
•
This section is intended for those who have ba-
sic knowledge and skill concerning the servic-
ing of Yamaha motorcycles (e.g., Yamaha
dealers, service engineers, etc.). Those who
have little knowledge and skill concerning ser-
vicing are requested not to undertake inspec-
tion, adjustment, disassembly, or reassembly
only by reference to this manual. It may lead to
servicing trouble and mechanical damage.
•
Make sure that the valve clearance is checked
or adjusted while the engine is cold (at room
temperature).
• While the valve clearance is checked or adjust-
ed, make sure that the piston is positioned in
the top dead center (TDC).
1. Remove:
•
Seat
• Side cover (left/right)
•
Air scoop (left/right)
Refer to “GENERAL CHASSIS” on page 4-1.
•
Fuel tank
Refer to “FUEL TANK” on page 7-1.
•
ECU
2. Remove:
•
Spark plug
• Cylinder head cover
Refer to “CAMSHAFT” on page 5-11.
3. Remove:
•
Timing mark accessing screw “1”
• Crankshaft end accessing screw “2”
•
O-ring
4. Check:
•
Valve clearance
Out of specification

Regulate.
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a. Turn the crankshaft counterclockwise with a
wrench.
Digital tachometer
90890-06760
Digital tachometer
YU-39951-B
Engine idling speed
1900–2100 r/min
Direction “a”
Engine idling speed

Decreases.
Direction “b”
Engine idling speed

Increases.
1
1
a
a
1
b
a
Valve clearance (cold)
Intake
0.12–0.19 mm (0.0047–0.0075 in)
Exhaust
0.17–0.24 mm (0.0067–0.0094 in)
1
2