Hi Andrew...The main bearing spacer should be 1.000"-1.010" long...Also ensure the oil flinger plate behind the drive side main bearing is flat and unworn..(where the bearing sits against it).
The crank will float within the cases when initially assembled but this float is taken up completely when the crankshaft shock absorber is tightened fully...
The crankshaft assembly is then 'clamped' against the outer drive side ball bearing which is a located in the case by a circlip...
Drive side bearings are NF305 (lipped roller)..6205 (single row ball)...both of these are metric and readily available from a good bearing factor...
I use a 6205 2RS (2 rubber seals) and remove the inner seal before fitting.
Timing side bearings are RLS7 (single row ball) and MRJA7/8" (lipped roller)..
Both of these are Imperial bearings. The Ball bearing is available...The lipped roller is now obsolete in a quality branded bearing...There are Chinese and Indian ones on the market....
This is the bearing that I have had remanufactured by a European manufacturer to the correct specification...
If you would like one mail me off forum....
All main bearings were originally to a 'C3' fit...However, these are getting harder to find as well...The 'C3' fit relates to the internal clearance of the bearing...It seems most crankcases have lost some 'fit' over the years and I have frequently run non C3 fits without any problems...If you can find them buy them...If not just ensure you buy a 'branded' bearing from a Japanese or European manufacturer....Note that 'Sterling' bearings may sound British but they are not...They are Indian....
Buy from a bearing factor (as opposed to a motorcycle shop) and stress these requirements....Many ' motorcycle trade' outlets are entirely happy to sell sub standard bearings... and they do...
For those that have already expressed an interest in the bearings I will be mailing you all this weekend with prices and shipping details...Ian
email (option): ian@wright52.plus.com