Yamaha F100B F100C Outboards Factory Service Manual, Page 119Get this manual
Cylinder head Checking the valve springs
1Measure the valve spring free length aReplace if out of specification
S60C5380
NOTE: Do not mix the valve train partsKeep them organized in their proper groups7Remove the intake valve and exhaust valvesValve spring free length limit a: 52.25 mm (2.057 in) 2Measure the valve spring tilt bReplace if out of specification
Valve spring tilt limit b: 2.6 mm (0.1 in)