Suzuki DF 90 Service Manual page 182

VALVE SPRING
Valve spring free length
Measure valve spring free length.
09900-20101 : Vernier calipers
Valve spring free length :
Standard :
IN & EX 42.7 mm (1.68 in.)
Service limit :
IN & EX 41.0 mm (1.61 in.)
If measurement exceeds service limit, replace valve spring.
Valve spring preload
Measure valve spring preload.
09900-20101 : Vernier calipers
Valve spring preload :
Standard :
IN & EX 167 –193 N (16.7 – 19.3 kg , 36.8 – 42.5 lbs.)
for 32.6 mm (1.28 in.)
Service limit :
IN & EX 151 N (15.1 kg, 33.3 lbs.)
for 32.6 mm (1.28 in.)
If measurement exceeds service limit, replace valve spring.
Valve spring squareness
Using a square and surface plate, measure each spring for
squareness (clearance between end of valve spring and
square).
09900-20101 : Vernier calipers
Valve spring squareness :
Service limit :
IN & EX 2.0 mm (0.08 in.)
If measurement exceeds service limit, replace valve spring.
POWER UNIT 6-37