BRP Johnson 4HP, Service Manual, Page: 17 / 185

1-11
GENERAL INFORMATION
*SPECIFICATIONS
Item Unit Data
VALVE/VALVE GUIDE
Valve diameter IN mm (in) 24.0 (0.94)
EX mm (in) 22.0 (0.87)
Valve clearance (Cold engine
condition) IN STD mm (in) 0.03 – 0.07 (0.001 – 0.003)
EX STD mm (in) 0.03 – 0.07 (0.001 – 0.003)
Valve seat angle IN — 15°, 45°
EX — 15°, 45°
Valve guide to valve stem
clearance IN STD mm (in) 0.025 – 0.052 (0.0010 – 0.0020)
Limit mm (in) 0.075 (0.0030)
EX STD mm (in) 0.045 – 0.072 (0.0018 – 0.0028)
Limit mm (in) 0.090 (0.0035)
Valve guide inside diameter IN,EX STD mm (in) 5.500 – 5.512 (0.2165 – 0.2170)
Valve guide protrusion IN,EX STD mm (in) 11.0 (0.43)
Valve stem outside diameter IN STD mm (in) 5.460 – 5.475 (0.2150 – 0.2156)
EX STD mm (in) 5.440 – 5.455 (0.2142 – 0.2148)
Valve stem deflection IN,EX Limit mm (in) 0.35 (0.014)
Valve stem runout IN,EX Limit mm (in) 0.05 (0.002)
Valve head radial runout IN,EX Limit mm (in) 0.08 (0.003)
Valve head thickness IN,EX STD mm (in) 1.0 (0.04)
Limit mm (in) 0.5 (0.02)
Valve seat contact width IN STD mm (in) 0.8 – 1.0 (0.03 – 0.04)
EX STD mm (in) 1.0 – 1.2 (0.04 – 0.05)
Valve spring free length STD mm (in) 29.5 (1.16)
Limit mm (in) 28.3 (1.11)
Valve spring tension STD N (kg, Ib) 139 – 159 (13.9 – 15.9, 30.6 – 35.1) for 19.3 mm (0.76 in)
Limit N (kg, Ib) 127 (12.7, 28.0) for 19.3 mm (0.76 in)