3-40 ENGINE
• Clean and assemble the head and valve components. Fill the
intake and exhaust ports with gasoline to check for leaks.
• If any leaks occur, inspect the valve seat and face for burrs or
other things that could prevent the valve from sealing.
VALVE SPRING
The force of the coil spring keeps the valve seat tight. Weak-
ened spring results in reduced engine power output, and often
accounts for the chattering noise coming from the valve mecha-
nism.
• Check the valve spring for proper strength by measuring its
free length and also by the force required to compress it.
• 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 spring.
Valve spring free length:
Service limit: (IN. & EX.) : 37.5 mm (1.48 in)
09900-20102: Vernier calipers
Valve spring tension (IN. & EX.):
Standard:
Approx. 147 N, 15.0 kgf/33.55 mm (33.1 lbs/1.32 in)
Always use extreme caution when handling gasoline.
33.55 mm
147 N
SAMPLE
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