AJS & Matchless Owners Club

Over tight primary chain pulling on the mainshaft? Slacken it off and give it a try.

Hi

Another bit of diagnosis - put the bike into gear, get someone to hold the clutch in and check for resistance when turning the rear wheel - no resistance eliminates a problem with the main shaft.

My next step would be to check the primary chain tension and if that is correct remove the primary chain case cover and chain, this will allow you to spin the engine independently of the gearbox and confirm whether the fault lies within the engine.

Did the previous owner re-build the engine? I'm suspecting that the main bearings may be out of alignment however it may be something far less sinister. Unfortunately you will need to strip the engine until it frees up and points to the component at fault.

I see you're in the same area as me - I'd be happy to have a look at the bike once we are free to meet and travel if its not sorted by then.

Edited to ask: Is this the same bike you reported to be overheating the casings? did you ever solve this? if not its more supporting evidence for an issue with the main bearings.

Regards Mick

Hi
first thing I would check is the tension of the primary chain, it should have at least
3/8" up and down movement, turn the engine over and check in at least three different
places in case of tight spots in the chain
Tony

Re Mick's last post, I rebuilt my G80S using anonymous (probably Chinese) main bearings and, although they dropped nicely into the heated crankcases, on cooling, they tightened up to the point it was impossible to rotate the inner races. I sourced a set of 'proper' branded (RWS as I remember) which solved the problem. That was over 10 years ago and branded bearings have become harder to find/more expensive, so if the engine was rebuilt recently, it's quite likely unbranded bearings were used. Disconnect primary drive, take out spark plug and check motor turns over freely. Andy

Hi again ,
Primary case off ,primary chain off , engine is fine no sign of any play or binding . Clutch basket excessive rock . Removed same and things are loose/worn at the shaft and possibly bodged to try to take up play
I have sourced another box fairly locally and intend to have a look at that when possible . Thanks again for all your input , I will let you know in time how it evolves from here.
Regards Allan

ajscomboman wrote:

clive wrote:I rarely use gaskets when assembling my gearboxes but if the end float is a problem perhaps you could try using them if your box is without them.

That's what the gaskets are there for Clive, to give sufficient end float! You're a naughty boy but not alone in doing this.

But if the gearbox is clapped out the gasket introduces too much end float! I bought mine off Roy after all

clive wrote: But if the gearbox is clapped out the gasket introduces too much end float! I bought mine off Roy after all

Ahh, that would make sense!

Excessive clutch rock is often due to wear in the chain wheel centre. This can be bushed and bored cheaply and easily if you have access to a lathe. I wrote an illustrated article for the Jampot on this job a few years ago. Can't remember year, but PM me and I can send a copy. Andy

Ok so far gearbox strip has shown dodgy bearings oval bushes wrong size clutch rollers and general bodge up . New parts being fitted so hopefully all good on the road test soon..... regards Allan

allanmg9 wrote:Ok so far gearbox strip has shown dodgy bearings oval bushes wrong size clutch rollers and general bodge up

Otherwise OK?