Main bearings are available from most major bearing factors. The drive side ball is available quite cheaply in the correct C3 fit. The other three are all available...the two lipped rollers, particularly the Imperial timing side one are now beginning to get expensive..and very expensive in the C3 fit.
To be honest though, with most engines having some wear present in the bearing housings, which affects the fit, I find they will run OK on the standard spec bearings.
Buy only 'branded' bearings from a known company...in other words a confirmed European or Japanese manufacturer and always specify this when making enquiries...A lot of suppliers..particularly in the motorcycle trade, are now supplying Russian, Indian and Chinese bearings cheaply and as direct equivalents..which in most cases they are certainly not. You get what you pay for as always...
I can also supply big ends...I supply an upgraded needle roller version with enhanced oil supply characteristics but still compatible with the BSA flywheels. Either as a 'rod kit' fitted to your rod and for you to refit to the flywheels or as a complete built up assembly using your flywheels..It should be noted however, that there is NO weakness in the original big end set up for use in any standard spec. engine...Ian
email (option): ian@wright52.plus.com
Hi, Ian /Dave thanks for offers of help.I have now stripped out the engine I wish to rebuild!! a M21 and have found slight up and down play on conrod but very excessive side to side play when you grip bottom of rod as much as 1/16th"
.I will seperate flywheels tomorrow & hope these are ok to use again as I dont have another pair for a M21.I think also I still have somewhere a complete set of Harley rollers as sold by Dave so maybe able to use them? As for mains I wouldnt fit a unamed bearing I would rather dig deep and pay for quality .Ian I might be interested in a conrod kit, I have rebuilt many of these cranks and have a jig for disassembly & rebuilding but have to use my mates lathe as mine wont take any thing this big in diameter.Will mail you direct if this is the case.thanks again Dave.