Suzuki LT-Z250 Service Manual page 73

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 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 both the inner and outer springs as a set.
% Valve spring free length (IN & EX)
Service Limit: 43.0 mm (1.69 in)
% Valve spring tension (IN & EX)
Standard: 256 29 4 N/36.6 mm
(26.1
57.5 6 6.1 lbs/1.44 in)
& 09900-20101: Vernier calipers
REASSEMBLY
Install each valve spring seat.
Apply engine oil to each oil seal and press-fit them into posi-
tion.
'
Do not reuse the oil seal.
Insert the valves, with their stems coated with molybdenum oil
solution all around and along the full stem length without any
break.
) MOLYBDENUM OIL SOLUTION
'
When inserting each valve into the valve guides, make
sure not to damage the lip of the oil seal.
Install the valve spring with the smaller pitch portion A facing
the cylinder head.
A Smaller pitch portion.
B Larger pitch portion.
30.0 kgf/36.6 mm,
ENGINE 3-31
256 294 N
36.6 mm
Cylinder head