Yamaha WR400F Fahrer- Und Wartungshandbuch Seite 332

VALVES AND VALVE SPRINGS
NOTE:
After every lapping operation be sure to
clean off all of the compound from the valve
face and valve seat.
Valve spring
1. Measure:
2. Measure:
b Installed length
3. Measure:
4 - 35
Apply Mechanic's blueing dye (Dykem) to
the valve face.
Install the valve into the cylinder head.
Press the valve through the valve guide
and onto the valve seat to make a clear
pattern.
Measure the valve seat width again. If the
valve seat width is out of specification,
reface and re-lap the valve seat.
Valve spring free length a
Out of specification → Replace.
Free length (valve spring):
Intake:
40.37 mm (1.59 in)
<Limit>: 39.4 mm (1.55 in)
Exhaust:
42.66 mm (1.68 in)
<Limit>: 41.7 mm (1.64 in)
Compressed spring force a
Out of specification → Replace.
Compressed spring force:
Intake:
117 ~ 134 kg (11.9 ~ 13.7 kg,
26.23 ~ 30.20 lb) at 32.86 mm
(1.29 in)
Exhaust:
126 ~ 138 N (12.9 ~ 14.1 kg,
28.44 ~ 31.08 lb) at 35.38 mm
(1.39 in)
Spring tilt a
Out of specification → Replace.
Spring tilt limit:
Intake:
2.5˚/1.8 mm (0.071 in)
Exhaust:
2.5˚/1.9 mm (0.075 in)
ENG