AJS & Matchless Owners Club

Hello people,could someone advise me please as i have just dicovered that i have an 18 inch wheel on the back and a 17 inch wheel on the front of my 1966 g2 250csr,is this correct,also found out that the clutch plates were put in back to front,with the small washer spacer which sits behind the basket on a shoulder was actually placed inside the basket resulting in the primary chain touching the casing as it ran ,cutting a groove into the casing (nightmare),next question is how many plates should there be.
regards TREVORIOUS

I am sure you should have 17" front and rear on the 250, 350 lightweight and other models had 18". You do not say how many friction and steel plates you have. You can check your parts list to discover what your bike should have. Perhaps also discover what you actually have got. If you have not got a parts list and instruction book. You really should get them. They will answer most question's you may have, instantly. These books were supplied with a new bike. You will probably need the 1960 parts list and supplements that followed stating parts that differ from 1960 onwards to 1966. All are archived here. www.archives.jampot.dk Also check out the workshop manual.

I thought that you should have 18" wheels as the CSR has the same teledraulic forks as the 350?? the standard 14 and CS versions had 17" wheels. I can't find a spares list or supplement for the CSR but if it has a duplex chain then you should have 4 double sided friction plates, 4 steel plates and one back plate the same as the 350. The CS (not the CSR) has a different arrangement see attached. It is a bit of a minefield as the gearbox main shafts are different so if someone has messed around with the box then you could have issues. But as I said, if you have the duplex chain version then I reckon the 350 clutch set up would be ok.

All 250s have 17" wheels (even the CSR).
I'm not sure what you mean by "washer spacer". There should not be any spacer behind the clutch basket.
If you have a duplex chain primary drive (which would be correct for a 250 CSR) and the chain is touching the chain case, then it is likely that your gearbox has the wrong mainshaft fitted: the mainshaft for duplex drive is longer than the one for the simplex chain.
Is it possible that your bike has a gearbox from a normal 250 or CS? This would explain the mismatch.

As been confirmed for lightweights, 250 17" 350 18" wheels, but bikes do get mixed up a bit. So not always straight forward to say what is actually wrong, could be 17" wheel and engine wrong??? not sure if that's possible. I have what I believe a gen 1966 250 G2CSR, I have only given the tank a spray, as all the Red in front of the seat has worn down to the silver undercoat. I have not gone through all my literature for the bike. The 1966 sales cat. will confirm G2 & G2CSR have 17" wheels Paul. http://archives.jampot.dk/promotional/S ... ochure.pdf
Somewhere I recall seeing the CS has one extra steel and friction clutch plate. This can be seen in the parts list. So if all parts are correct and assembled correctly, the chain should not be foul the chain case.
There is uncertainty about a part which is referred to. This confirms my saying you must have all the literature for a bike. You can then refer to a part by the name given to it by AMC. This aids communication and better understanding. The part name and number is also important information needed if buying / searching for, new / replacement parts.

Thanks for the brochure link... hadn't seen that before, learnt something there, not only about wheel size but the fact that the later bikes had different gear ratios. The few boxes I have seen/had have had the same gears withinn, something to note when swapping internals around

Ozmadman wrote:Thanks for the brochure link... hadn't seen that before, learnt something there, not only about wheel size but the fact that the later bikes had different gear ratios. The few boxes I have seen/had have had the same gears withinn, something to note when sapping internals around

Its an A.M.C. sales cat. Paul. ( AJS/Matchless/Norton ) So perhaps gets overlooked when looking for e.g. an AJS 1966 sales cat. I am not sure if there were any other years, when there was an A. M. C. sales cat.

Just a thought on the "closer gear ratios" on the CSR: while this might be technically correct, is it just the result of using a larger engine sprocket (i.e. 22 tooth instead of 17)?

That's what the manual seems to imply and the parts list backs this up:
First gear pair 041279 + 044080 (2.92:1) was fitted to all models (except the CS)
First gear pair 041197 + 042954 (2.42:1) was only fitted to CS models

Second (1.85:1), third (1.30:1) and fourth (1:1) were apparently the same physical ratios for all models

The effective ratios according to the manual are as follows:
250CS: 21.62, 16.6, 11.63, 8.95:1
350 and 250CSR: 18.68, 11.82, 8.32, 6.39:1

So the 1966 marketing literature is correct when it says "gear ratios are higher and closer" for the CSR, but that doesn't mean they actually changed the gearbox internals!

Interestingly, that means the CS is the only model with a "proper" close ratio gearbox. Hmm, that higher first gear might work quite well when used with a CSR primary and final drive...

Oh, forget all of that!

The 1966 parts list makes no mention of different gears for the CSR, but p.6 of the F Neill manual says the physical ratios for the 1965/66 CSR are:
2.76, 1.75, 1.24, 1:1

Making effective ratios of:
17.97, 11.68, 8.05, 6.5:1

Which implies another set of 1st, 2nd and 3rd gears possibly were used in these models.
Anybody know the the part numbers were? I've not come across different ratios in any of my gearboxes, but that doesn't mean they don't exist.

Perhaps this an error? On the very next page, the F Neill manual says the ratios are as per the factory manual i.e. 2.92, 1.85, 1.30, 1:1

I think I need to count some teeth and work this out properly...

Found these, brochure clearly says " internal gear ratios have been changed"