Suzuki kq500 Service Manual page 191

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
(A): 09900–20101 (Vernier calipers (150 mm))
Valve spring free length (IN. & EX.)
Service limit: 38.8 mm (1.53 in)
Valve spring tension (IN. & EX.)
Standard: 182 – 210 N (18.6 – 21.4 kgf, 41.0 – 47.2
Ibs)/31.5 mm (1.24 in)
Tension "a"
182 – 210 N
(18.6 – 21.4 kgf, 41.0 – 47.2 lbs)
(A)
I649G1140237-03
" a"
"b"
I649G1140238-03
Length "b"
31.5 mm
(1.24 in)
Valve Seat Width
1) Visually check for valve seat width on each valve
face. If the valve face has worn abnormally, replace
the valve.
2) Coat the valve seat with a red lead (Prussian Blue)
and set the valve in place.
3) Rotate the valve with light pressure.
Special tool
(A): 09916–10911 (Valve lapper set)
4) Check that the transferred red lead (blue) on the
valve face is uniform all around and in center of the
valve face.
If the seat width "a" measured exceeds the standard
value, or seat width is not uniform reface the seat
using the seat cutter. Refer to "Valve Seat Repair
(Page 1D-46)".
Valve seat width "a" (IN. & EX.)
Standard: 0.9 – 1.1 mm (0.035 – 0.043 in)
"a"
Engine Mechanical: 1D-43
(A)
I931H1140286-01
I649G1140246-02