Gearbox issues

[spike123]

Hi guys
I've just tested my a65 1967 and found trying to get from second into third not selecting and fourth was just none existent any ideas

[DAVE BRADY]

Hi Spike,

Has this just started to happen or have you have the selector mechanism out?

Dave.

[spike123]

No first trip
I haven't dismantled the gearbox as it seemed to select ok without the engine running, I bought the bike but haven't ridden it as I've given it a rebore and crank regrind, so first run out today with this issue. The engine seems to be a miss mash engine, the left crankcase had no timing plate for static timing and they put a four spring clutch in it, so had to reduce spending so that's why I didn't touch the gear box as I thought it was ok
Mark

[DAVE BRADY]

Hi Mark,

Usually selection issues are linked to the actual selector plungers that move the cam plate or the the return spring.
If the plunger springs are weak or the grub screw holding the plungers in place has become loose then selection issues will be the result.  If the return spring acting on the selector quadrant is weak this can stop the plungers from returning to the correct place. It is also possible for a plunger to get stuck.  Do you know if the gears selected properly when the engine was last run?
If it was OK, then when you put everything back after the crank regrind something was put back differently and my initial guess would be the gear change return spring.  They can have a bias that can cause selection problems.
Perhaps try flipping it over and see what happens.  If it looks like it is the plungers then the casing will have to be removed again to get to them.

Dave.

[spike123]

The bike has not run till the other day , so not sure , I'll take the outer cover off and have a look as I've said it selects gears ok when engine is not running , I've crossed the return spring over and the gear change dose return, so could've plunger
Thanks

[DAVE BRADY]

Hi Spike,

I have attached a Service Bulletin that was posted previously.  It may be useful if you have to delve deeper in to the gearbox.

Dave.