Valve Spring - BRP Johnson 4HP Service Manual

POWERHEAD

VALVE SPRING

5. Ream the valve guide bore with the 5.5 mm reamer.
 Valve guide reamer (φ5,5 mm)
Reamer handle
NOTE:
Clean and oil the valve guide bore after reaming.
VALVE SPRING
Valve spring free length
Measure the valve spring free length.
 Vernier calipers
Valve spring free length:
Standard: IN and EX
Service limit: IN and EX 28.3 mm (1.11 in)
If the measurement exceeds the service limit, replace the
valve spring.
Valve spring preload
Measure the valve spring preload.
 Vernier calipers
Valve spring preload:
Standard:
IN and EX 139 – 159 N (13.9 – 15.9 kg, 30.6 –
35.1 lbs) for 19.3 mm (0.76 in)
Service limit:
IN and EX 127 N (12.7 kg, 28.0 lbs) for 19.3 mm
(0.76 in)
If the measurement exceeds the service limit, replace the
valve spring.
6-18
29.5 mm (1.16 in)