I recently inherited a 1972 Combat Commando. On stiff acceleration the bike jumps out of first gear. I replaced the first gear layshaft bushing.( suggested by the Norton INOA list) This did not solve the problem. Any suggestions on what I should look for next? Thanks in advance for your kind consideration of my problem.
John R. Gough II '65 Velocette MSS '55 BSA Super Rocket
Before you take apart your gearbox, it's a good idea to check the play in the sleeve bearing. That's the big one on the drive side. first remove the primary inspection plug (middle plug) and move the chain up & down (hard). With your other hand feel the gearbox sprocket. A little bit of motion of the drive chain is normal, but the sprocket should not have any noticeable fore and aft movement. Or clunk-clunk feel. When these bearings go bad, they spin in the case. The repair for this would depend on just how much damage was done. If the bearing is loose, you will need to take apart the primary also to gain access to it. Hope this helps Cheers Dennis B P.S. The article that Fred Eaton at Old Britts did is excellent. However he said to use Loctite Red for a loose sleeve bearing, I would suggest using Loctite Sleeve Retainer 640.