Yamaha MX250 - Checking the Valve Seats

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ENGINE
VALVE
6.
Measure:
• Valve spring tilt “a”
Out of specifications  Replace.
7.
Check:
• Valve spring contact surface “a”
More than 2/3 of the contact surface does not con-
tact  Replace.
CHECKING THE VALVE SEATS
The following procedure applies to all of the valves and
valve seats.
1.
Remove carbon deposits from the valve face and
valve seat.
2.
Apply a small amount of coarse mechanic’s blue lay-
out fluid to the valve face “a”.
Installed compression spring force (Intake):
91.20–104.93 N (9.12–10.49 kgf, 20.50–23.59
lbf)
Installed compression spring force (Exhaust):
91.20–104.93 N (9.12–10.49 kgf, 20.50–23.59
lbf)
Installed length (Intake):
29.0 mm (1.1417 in)
Installed length (Exhaust):
29.0 mm (1.1417 in)
a
Tilt limit:
1.7 mm (0.0669 in)
a
a