Suzuki GW250 Service Manual page 79

VALVE STEM END CONDITION
• Inspect the valve stem end face for pitting and wear. If pitting
or wear is present, resurface the valve stem end.
• Make sure that the length A is not less than 2.2 mm (0.09 in).
If this length becomes less than 2.2 mm (0.09 in), replace the
valve.
 Valve stem end length A:
Service Limit (IN. & EX.): 2.2 mm (0.09 in)
 09900-20101: Vernier calipers (150 mm)
VALVE SPRING
The force of the coil spring keeps the valve seat tight. Weak-
ened spring result in reduced engine power output, and often
account for the chattering noise coming from the valve mecha-
nism.
• Check the valve spring for proper strength by measuring their
free length and also by the force required to compress them.
• If the spring length is less than the service limit, or if the force
required to compress the spring does not fall within the range
specified, replace the valve spring.
 Valve spring free length (IN. & EX.):
Service Limit (INNER): 32.1 mm (1.26 in)
(OUTER): 31.8 mm (1.25 in)
 09900-20101: Vernier calipers (150 mm)
 Valve spring tension (IN. & EX.):
Standard (INNER): 58.2 – 71.2 N (6.0 – 7.3 kgf,
Standard (OUTER): 158.7 – 182.5 N (16.2 – 18.6 kgf,
REASSEMBLY
Reassemble the cylinder head in the reverse order of diassem-
bly. Pay attention to the following points:
• Install the valve spring seat 1.
• Apply molybdenum oil solution to the new oil seal 2, and
press-fit it into position.
 MOLYBDENUM OIL SOLUTION
13.2 – 16.1 lbs)/28.0 mm (1.10 in)
35.7 – 41.0 lbs)/31.5 mm (1.24in)
ENGINE 3-31