Service Specifications

VALVES
Valve Lift
Exhaust 10.528 mm (0.4145 inch)
Intake 10.350 mm (0.4075 inch)
Intake Valve Timing
Opens 15.40 (BTDC)
Closes 580 (ABDC)
Duration 253.30
Exhaust Valve Timing
Opens 52.80 (BBDC)
Closes 26.20 (ATDC)
Duration 2590
Valve Overlap 41.60
Valve Length (Overall)
Intake 124.435 - 125.070 mm (4.899 - 4.924 inch)
Exhaust 125.120 - 125.755 mm (4.927 - 4.952 inch)
Valve Stem Diameter 7.899 - 7.925 mm (0.311 - 0.312 inch)
Stem to Guide Clearance 0.025 - 0.076 mm (0.001 - 0.003 inch)
Valve Face Angle
Intake 46.5°
Exhaust 46.5°
Valve Head Diameter
Intake 48.387 - 48.641 mm (1.905 - 1.915 inch)
Exhaust 37.973 - 38.227 mm (1.495 - 1.505 inch)
Tip Refinishing (Max Allowable) 0.25 mm (0.010 inch)
VALVE SPRINGS
Free Length (Approx.) 47.65 mm (1.876 inch)
Spring Load
Valve Closed 316 to 351 N @ 41.656 mm (71 to 79 Lbs. @ 1.64 inch)
Valve Open 898.6 to 969.7 N @ 30.89 mm (202 to 218 Lbs. @ 1.216 inch)
Inside Diameter (Top) 21.0 mm to 21.51 mm (0.827 to 0.847 inch)
Installed Height 41.656 mm (1.640 inch)
CYLINDER HEAD
Combustion Chamber 49.9 to 52.9 cc (3.04 to 3.23 cu. inch)
Valve Guide I.D. (Integral) 7.95 to 7.97 mm (0.313 to 0.314 inch)
Valve Seat Angle
Intake 44.5°
Exhaust 44.5°
Valve Seat Width 1.01 to 1.52 mm (0.040 to 0.060 inch)
Valve Seat Runout 0.064 mm (0.0025 inch)
Flatness 0.03 mm per 25 mm (0.001 in. per 1 inch) 0.05 mm per 152 mm (0.002 in. per 6 inch)
Flatness (Max) 0.20 mm for total length (0.008 in. for total length)