Topic: Gearbox CB400/4

[thumper]

Hi Guys I would like some info on CB400/4 (1) I have rebuilt a few Triumph engines and would like to rebuild my 77 engine. The Gearbox is snatching on changing gear sunds like the Chain is jumping a sprocket. Can these engines be rebored. I am just back from a Charity Run and it seems I have only 5 gears. At 50mph the engine is at 4000 rpm. Any info appreciated. Chain tension is ok with new chain and Sprockets.

[camelman]

Those transmissions do wear out and the gears get sloppy on the shafts. I have one on a 350 (similar to the 400) that is so worn it won't go into first or neutral. The real culprit for you is probably a worn clutch basket. It causes inconsistent clutch engagement, rough clutch h engagement, false neutrals and clunky shifts. It can be fixed by removing the clutch basket and filing the fingers smooth.

[thumper]

Thanks for that, Sounds a good one I will have a Go at it and keep you posted

[poodleracer]

How big of a job is the clutch removal? I have all the issues you just stated. It seems to be less clunky when its hot but the clutch pull is very heavy, and the bike will not go into neutral while stopped. A clutch rebuild is on my to do list but I'm a little worried about splitting the cases and getting in over my head. I rebuilt the carbs no problem and I am mechanically inclined, just inexperienced with the gear box/clutch? Any advice?

[camelman]

The clutch is under the right side engine cover. No need to split the cases, and it is an easy job. Takes me about 30 minutes to change a clutch out. Add an hour to file the clutch basket fingers.

[poodleracer]

Oh really?
Sweet, thanks for the info that will be my next project. I'm sure there is a thread with some info here somewhere.