Jumping out of gear

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Apr 2, 2008
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My early 850 for some time has been unwilling to positively shift from neutrat to first. It is fine when going from 2nd to first but if I put it in neutral (at a light, etc), it doen't readinly go into first. On this board, someone suggested leaving pressure on the shift lever while releasing the clutch and this seems to do the trick. This past weekend, I took it on a day long outing on some steep curvy roads and just on one occasion, it jumped out of pulling a tight curve on a steep hill. For most of the day and on similar terrain it did fine. My question is:

Are these two issues related and is it a sign of badly worn sycros or just what?

Thanks for any help.
There are no syncros in a norton box, it is a constant mesh type box eg all the gears are meshed in pairs permanently.

I'd say you two issues could be connected eg the 1st gear bush may be worn. Only a strip down will show.
Hi there, could be effectivly the dogs of the second layshaft gear which are a "bit" worn, did you have some end paly through the kick start shaft, if any you could try to shim the layshaft (as per old brit's way), that could help.....search in that forum, there were some topics about. good luck.
It could jump out if the dogs were worn but I don't see why that would make it difficult to engage. To be honest, I'd suspect clutch drag. The one time that it jumped out could be because it didn't go in properly in the first place.

The layshaft engagement for first is not undercut.

Your problem may be cured by something as simple as giving the clutch a good clean and adjusting it (the centre may be notched though).
I do have some play in my kick start shaft so I will definitely shim that and see if that helps. I have been the full route with the clutch and I would have to say right now that there is no drag and no slip. The clutch center looked pretty good and the complete clutch clean did nothing to change the neutral to first issue at all. Since the bike only jumped out of gear the once, the thought that it wasn't fully engaged that particular time could hopefully be the answer. On the not shifting into first from neutral, someone at some point said to me that they had heard something about as I remember, a cracked spring on the shifter plate or something like that. Does that mean anything to anyone? Thanks for all of the good ideas.
I'm with 79x100 here. I had the same issue, with the box jumping out of first regularly. Once I'd gone to my belt drive and new plates and centre, the problem disappeared completely. So. I can't tell you what it was but it certainly wasn't a gearbox problem, as such.
Sorry but I can't seem to find the Old Britts article on shimming the kick start mechanism. Does anyone have it or know its whereabouts?
hey yellow cad! as i know....when it jumps out of gear when you are going on load [in example driving up a hill or when you are hard speeding up] then [i had the problem with a bsa - the same gearbox technique] it is because the gear pinions [1st pinion layshaft to 1st pinion main in your case] are not parallel to each other.
Because they are heavy worn or there is too much play in the bushes/bearings of the shafts....
hard to engaging a gear is in my opinion mainly a clutch problem. some thoughts....controll the angle of the clutch release arm....maybe you are on limit of clutch operation....

have a nice day, chris
old britts kicker shim step under tech section assy gearbox
u can use front -010 iso shims I thought that was pretty trick
Check your detent and spring that screws out the bottom of the tranny. Even and 1/8th to a 1/16th of an inch shy of spec. will have an effect on how the gears wor under load. I replace my plug and spring and no more slipping out of gear. I am sure that this only one of many solution
My early 850 for some time has been unwilling to positively shift from neutrat to first.

I'm correct in thinking the problem is not jummping out of first but not fully selecting, there's no crunch etc it feels like it's gone in just when you let the clutch go there isn't any drive?

If so, clutch drag can cause this, but another that caught me out after I first fitted a primary belt drive was; heat expanded the alloy pulleys, the belt got too tight and loaded up the sleeve gear bushes. Slackening the belt cured the problem.

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