Gear popping out of 1st into neutral

the gear box I originally had on the G80cs would slip out of first gear to the extent in reallity it was only a 3 speed box, the problem was wear on ist gear dogs, once this gear was replace the box worked perfectly, it certainly wasn't doing 5K when this happened though. kind regards

I mean 1st gear dog, I have tried to edit this but the edit formula seems so bloody confusing I don't know where the posting has gone! kind regards

If the layshaft inner bearing has been upgraded to a roller the layshaft is made floating instead of fixed, this can result in 1st gear jumping out into neutral. Cure is to shim the layshaft at the kickstart spindle. While you are in there you can check the gears and dogs for wear.

Gear box problems require prompt investigation, worn dogs can lead to friction on the selectors which can then seieze.

5000 rpm in first ! that's going for it. My money is on the gear not being fully engaged in the first place. Try this. as you select first, begin letting the clutch out with pressure on the gear pedal. the gear might then fully engage. then take it to your 5000 rpm and see if it slips out. if it doesn't. the gear previously hasn't been fully selected. if it still slips out then the dogs might be an issue.

The Commando box is quite nice and close from second to fourth - on the road it is effectively a three-speeder. It shouldn't be jumping out but I suspect that most of us short-shift from first to second and then give it some !

Main shaft first gear is very small and wears quickly, as Richard says second and onwards for spirited riding. If you do the traffic lights drag race, fit a 19 tooth gearbox sprocket.

Keeping up with the big boys on 1000cc+ bikes on a 40 year old bike. Best budget for an engine rebuild to go with your gearbox.

I think that what he is trying to tell you is that when you engage first gear, the gears are not being fully engaged. Then, when you try to pull away the pressure on the gears causes then to disengage themselves.

Check the engagement like Richard says.

Mike

Ok i can answer this with regard to the cam plate, to get to the cam plate you have to take off the outer cover followed by the inner cover, so if you have had the gearbox apart there is a chance the cam plate is a tooth out, i know i made that mistake and found i could only select 2 gears with the others sort of engaging.

If your bike was selecting gear ok and the gearbox has not been stripped imo its not the cam plate.

The window referred to can be seen once the first cover has been removed there will be a fork facing you (quadrant) with a lose barrel with a hole in, that the gear lever engages (knuckle pin roller). When you select gear the fork will move up and down and must go to both extremes of that window.

if the gearbox has been apart and you need to move the quadrant by 1 or 2 teeth it can be done without taking the sleeve gear out.