classic motorcycle forum

Thanks Blue - I think the only way I will find out what is going on is to take off the timing casing and have a look at it all but thanks for the pointers ! I called SRM and the chap I talked to says that they engrave a 4 digit job number onto the inside of the timing case so I will be able to see when I take it off - I will also be looking for the roller main bearing - if its still a bush then I will know that the SRM story is a load of tosh  

I have recently bought a 1955 A10 with Plunger frame. The engine starts and runs well but when hot the engine is rather rattly from the timing side. I am told the engine was rebuilt with an SRM crank conversion and that spitfire cams have been fitted. Being unfamiliar with the A10 engine I was wondering how rattly these engines tend to be or should there be very little rattle at all ! :-/

Thanks Blue for that very useful info - I have also just had an email conversation with a very old mate of mine who says that he can recall the 650 twin also had a weak bottom end due to crankshaft whip at high speed - presumabably the third main bearing that was added was in an effort to counteract this problem. Ok if you keep the revs down, but buying a bike with an engine that hasn't been re-built or at least re-built properly could be risky!!