Service Manual

Maintenance Specifications

Item Specification Service Limit

Maximum speed (no load) 3730 - 3830 rpm -

Compression (at 1400 rpm) 1.25MPa -

Cylinder bore I.D. 78.0mm 78.025mm

Cylinder head cover flatness - 0.10mm

Piston skirt O.D. 77.962 – 77.98mm 77.86mm

Piston to cylinder clearance 0.020 – 0.058mm 0.12mm

Piston pin bore I.D. 17.004mm 17.048mm

Piston pin O.D. 16.998mm 16.954mm

Pin to pin bore clearance 0.006 – 0. 018mm 0.08mm

Piston ring side clearance 0.03 – 0.07mm 0.135mm

Piston ring gap 0.20 – 0.35mm 1.0mm

Piston oil ring gap 0.20 – 0.70mm 1.0mm

Piston ring width 1.197mm 0.85mm

Piston oil ring width 1.996mm 1.675mm

Connecting rod piston end I.D. 17.005mm 17.046mm

Connecting rod crank end I.D. 40.010mm 40.060mm

Oil clearance 0.030 – 0.054mm 0.12mm

Crank end side clearance 0.10 – 0.50mm 1.1mm

Crankshaft pin O.D. 39.998mm 39.920mm

Intake valve clearance 0.015 ± 0.05mm -

Exhaust valve clearance 0.020 ± 0.05mm -

Intake valve stem O.D. 6.475mm 6.380mm

Exhaust valve stem O.D. 6.475mm 6.320mm

Valve guide I.D. 6.50mm 6.562mm

Intake valve stem clearance 0.0265 – 0.0340mm 0.10mm

Exhaust valve stem clearance 0.0265 – 0.0340mm 0.10mm

Valve seat width 3.8 - 4.0mm 5.0mm

Valve spring free length 39.4mm 38.0mm

Camshaft intake lobe 18.006mm 17.940mm

Camshaft exhaust lobe 18.006mm 17.940mm

Camshaft journal O.D. 13.275mm 13.225mm

Camshaft bracket I.D. 13.305mm 13.350mm

Carburetor main jet 1.08mm -

Spark plug gap 0.70 – 0.80mm -

Spark plug wire resistance 3.0 – 7.5kΩ -

Primary ignition coil resistance 1.5 – 1.9Ω -

Secondary ignition coil resistance 6.6 – 8.6kΩ -

Ignition coil air gap 0.2 – 0.6mm -

Stator winding resistance 0.20Ω ± 10% at 25°C -

Stator auxiliary winding resistance 0.89Ω ± 10% at 25°C -

Rotor excitation winding resistance 45.0Ω ± 10% at 25°C -

Carbon brush length 10mm 7mm