Hi Al. Glad to get comment from a dirt under the finger nails guy like myself. Well as I understand it the C3 rated bearing is loose compared to the standard tolerance one because when the inner race is an interference fit to the crankshaft the heat transfer will close up a fair bit of the play. The dilemma is that we are told to replace like with like and not needlessly replace a standard one with C3 but as the old bearings are not marked with this rating how are we to know? So far I have rebuilt a lot of motorcycle engines, mostly Italian and normal bearings have given me no trouble what so ever, mind you they are all four strokes so the oil would have a cooling effect. Re the casings gasket, again all the motors I have rebuilt to this point have had a gasket[schmitt included] so it came as a surprise to find it absent, thanks for pointing out that as Tom Jones would say" its not unusual" . I still will not be able to resist applying at least a smear of wellseal. That reminds me of a chat I had with a mechanic up at Duxford last year, I asked him if it was true that the Merlin as used in there Spitfire had no head gasket to which he replied yes but seventy year old ones appreciate a dollup of Wellseal!
Ahh Rusty Chrome, just spotted your post, that answers both questions. Many thanks indeed!
