Valves And Valve Springs; Removing The Valves - Yamaha YZ 2017 Series Owner's Service Manual

REMOVING THE VALVES

EASB29B223
TIP
Before removing the internal parts of the cylin-
der head (e.g., valves, valve springs, valve
seats), make sure that the valves are properly
sealed.
1. Remove:
• Valve lifter "1"
• Adjusting pad "2"
TIP
• Place a cloth in the timing chain space to pre-
vent adjusting pads from falling into the crank-
case.
• Make a note of the positions of valve lifters
and adjusting pads so that they can be rein-
stalled in their original places.
Valve lapper
90890-04101
Valve lapping tool
YM-A8998
2
2. Check:
• Valve sealing
Leakage at the valve seat  Check the
valve face, the valve seat, and the valve seat
contact width.
Refer to "CHECKING THE VALVE SEATS"
on page 5-27.

VALVES AND VALVE SPRINGS

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a. Pour a clean solvent "a" into the intake and
exhaust ports.
b. Check that the valves are properly sealed.
TIP
Check that there are no kerosene leaks from
the valve seat "1".
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3. Remove:
• Valve cotter "1"
TIP
Remove the valve cotters by compressing the
valve spring with the valve spring compressor
"2" and the valve spring compressor adapter
1
"3".
4. Remove:
• Valve spring retainer "1"
• Valve spring "2"
• Valve "3"
• Valve stem seal "4"
• Valve spring seat "5"
5-24
1
a
a
Valve spring compressor
90890-04019
Valve spring compressor
YM-04019
Valve spring compressor attach-
ment
90890-04108
Valve spring compressor adapter
22 mm
YM-04108