Suzuki AN400 Service Manual page 79

VALVE STEM END CONDITION
• Inspect the valve stem end face for pitting and wear.
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If pitting or wear is present, resurface the valve stem
end. Make sure that the length A is not less than 1.7
mm. If this length becomes less than 1.7 mm, replace
the valve.
' Valve stem end length: Service Limit: 1.7 mm (0.07 in)
% 09900-20102: Vernier calipers
VALVE SPRING INSPECTION
• The force of the coil spring keeps the valve seat tight. A weak-
ened spring results in reduced engine power output and often
accounts for the chattering noise coming from the valve
mechanism.
• Inspect 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 speci-
fied range, replace the spring.
% 09900-20102: Vernier calipers
' Valve spring free length (IN & EX):
Service Limit: 38.8 mm (1.53 in)
' Valve spring tension (IN & EX):
Standard: 182 – 210N (18.2 – 21.0 kgf) /31.5 mm
(40.1 – 46.3 lbs/1.24 in)
ENGINE 3-33