Suzuki LT-A400, Service Manual

Page: 99 / 502

Engine Mechanical: 1D-25
Valve Stem Wear
If valve stem is worn down to the limit, as Measured with
a micrometer. where the clearance is found to be in
excess of the limit indicated replace the valve, if the stem
is within the limit, then replace the guide. After replacing
valve or valve guide, be sure to re-check the clearance.
Special tool
: 09900–20205 (Micrometer (0 – 25 mm))
Valve stem O.D.
Standard (IN.): 4.975 – 4.990 mm (0.1959 – 0.1965 in)
Standard (EX.): 4.955 – 4.970 mm (0.1951 – 0.1957 in)
Valve Stem End Condition
Inspect the valve stem end face for pitting and wear. If
pitting or wear of the stem end face are present, the
valve stem end may be resurfaced, providing that the
length “A” will not be reduced to less than the service
limit. If this length becomes less than the service limit,
the valve must be replaced.
Valve stem end length
Service limit: 2.3 mm (0.09 in)
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 spring does not fall within the specified range,
replace the valve spring.
Special tool
: 09900–20101 (Vernier calipers (1/15 mm, 150
mm))
Valve spring free length (IN. & EX.)
Service limit: 40.9 mm (1.61 in)
Valve spring tension (IN. & EX.)
Approx. 196 N (20.0 kgf, 44.1 lbs) at length 31.5 mm
(1.24 in)
I827H1140064-01
“A”
I827H1140065-01
Tension “a” Length “b”
Approx. 196 N
(20.0 kgf, 44.1 lbs)
31.5 mm
(1.24 in)
I827H1140066-01
“ a ”
“ b ”
I827H1140067-01