Hitchcocks Forum

My 2008 Bullet 500 Sixty-5 is jumping out of 4th gear, sometimes it sticks first time but then jumps out under load and keeps jumping in and out every time I put it into 5th. All other gears are ok.
I've just stripped the gear box down and have noticed that the selector is sticky in the groove on the gear, there are burn marks on both the gear and the selector claw, and a burr has started forming on the edge of the Selector claw.
What would cause this? I've not replaced either part, but have stripped the gear box down before to fix a missing tooth and 2nd gear.
Any ideas why this is happening? I was going to clean up the burr and carefully grind al little material off so it runs smoothly in the groove or should I just replace both he gear and selector?
Thanks
Ian

Hi Ian, on the 5 speed gearboxes I have worked on to fix jumping out of gear and bad selection, the most common gear to wear and give trouble are the mainshaft 2nd gear [and its' selector fork] and the mainshaft sleeve gear [the one the gearbox sprocket fits over the end of]. check for rounded off corners, or edges on the engagement dogs on all gears which have them and the mating faces of their partners. Also check the spindle which the selector forks slide along is fully located and held in place by its' circlip, which is behind the carrier, or end plate - the end of the spindle should be just below the face of the carrier plate, if it is sticking out, it has slipped through the circlip and the other end is out of the hole at the far end of the gearbox casing and if this is the case, the selectors will be waggling about. One more possibility is the two needle races in the mainshaft sleeve gear are just a light press fit and they can 'creep' along in exceptional circumstances and go into a void space inside the sleeve gear, thus allowing the sleeve gear to wobble on the mainshaft and cause the machine to jump out of top gear - if your gearbox sprocket nut is done up tight, but the gearbox sprocket can be wobbled sideways, this may be the cause. I have modified a few 5 speed gearboxes to overcome these problems. You need to replace that selector fork and any other suspect parts, though. Our hosts sell optional sizes of selector stop pins for these gearboxes and these can help with over / under selection at the pedal. Regards, Paul.