Valve Spring - HYOSUNG RT 125 D Service Manual

3-15 ENGINE
⊙ ⊙ VALVE SPRING
The force of the coil spring keeps the valve seat tight.
A weakened spring results in reduced engine power
output and often accounts for the chattering noise
coming from the valve mechanism.
Check the valve springs 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 valve spring is not within specification,
replace the valve spring.
Cylinder head
Valve spring free
length (IN. & EX.)
distortion
Vernier calipers : 09900-20101
Cylinder head
distortion
Valve spring tension
(IN. & EX.)
⊙ ⊙ CYLINDER DISTORTION
Check the gasketed surface of the cylinder for
distortion using a straightedge and thickness gauge,
taking a clearance reading at several places as
indicated.
If the largest reading at any position of the
straightedge exceeds the limit, replace the cylinder.
Cylinder distortion
Thickness gauge : 09900-20806
Service limit
37.80 mm (1.488 in)
Standard
12.1 ~ 13.9 kgf
(26.68 ~ 30.64 lbs)
at length 33.7 mm (1.33 in)
Service limit
0.05 mm (0.002 in)
38