Cub Cadet Challenger 500, Service Manual

Page: 97 / 244

Engine
4 ‐ 10
Inspect

Valve Sealing:
(look for leaks at the seat)
Pour a combustion chamber
cleaner into the intake track.
Check the intake side (1), there
should be no leakage at the valve
seat (2).
If leakage is found, the valves and the
valve seats need to be ground and lapped.
Measure valve stem to valve guide
clearance.
Limit Intake 0.12mm
Exhaust 0.14mm
Measure the margin thickness.
Both Intake and Exhaust
0.85 – 1.15 mm
Measure valve stem runout
Runout Limit: 0.01 mm
Whenever a valve is removed, always
replace the valve guide seal.
If the valve needs to be replaced, replace
the valve guide as well.
Measure the valve spring free length and
squareness.
Valve spring free length:
Intake: 32.5mm Exhaust: 36.2mm
Valve spring squareness:
Intake: 0.10mm Exhaust: 0.10mm
Measure the compressed spring force
Intake: 100.0 - 115.7 N at 27.5 mm
Exhaust: 120.6 - 138.3 N at 31.0 mm