Valves And Valve Springs; Removing The Valves - Yamaha YZ 2015 Series Owner's Service Manual

REMOVING THE VALVES

EASB291226
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
width.
Refer to "CHECKING THE VALVE SEATS"
on page 5-27.
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a. Pour a clean solvent "a" into the intake and
exhaust ports.

VALVES AND VALVE SPRINGS

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
"3".
1
4. Remove:
• Valve spring retainer "1"
• Valve spring "2"
• Valve "3"
• Valve stem seat "4"
• Valve spring seat "5"
5-25
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