Cylinder head bolt torque values

Head bolts

Ian Wright advises the following for WM20 head bolts. This is the procedure. Place copper head gasket with the seam upwards. place bolts in head according to diagram in the WM20 manual and turn down the bolts by hand or loosely with ratchet. Then torque down in sequence as shown in diagram to 28~30 foot pounds with a torque wrench. Run engine until warm (just run at idle, no riding). let the engine sit until cold then re-torque to 28~30 foot pounds once again. run engine once more until warm as described above then sit until cold. Re-torque to 28~30 ft. lbs. After this take the bike for a spin for 10 miles and let engine cool once more, check torque. That'll do it.


Ian Wright


Crankpin nuts

According to Dave Plumb 100 ft/lb should be about right for the crankpin nuts.