Disaster

[A10Boy]

Given that cranks are now a limited resource, and bushes can be easily made, it makes sense to grind the minimum from the crank journal [enough to clean it up], and machine whatever is required to get to the  1 1/2 thou clearance from the bush. If the bush doesnt have enough meat to do this, replacements are cheap.

[orabanda]

In this instance, 6 of one, half a dozen of the other.
Hence my qualification "If you have enough material on the crankshaft journal......."

If either the bush is not machined true, or replaced, there will be tears!

Richard

[A10Boy]

Mark, good luck with whichever way you choose.

[mark]

Thanks guys, Will let you know how it turns out.
Mark

[mark]

Well it's finally on the road. The crank turned out well, we used the existing bush. Treated it to some new pistons as the bore had some light corrosion marks that the honing didn't quite remove. This turned out to be disaster #2. The pistons came from a well known Melbourne supplier of British motorcycle parts and he said that he had never had a problem with them. The ring gap on one ring was 25 thou and a couple of others were also too big so I exchanged them for better ones.  It pumped so much oil past the rings that it was dripping from the exhaust. He begrudgingly gave me another pair of oil rings which did exactly the same thing. I should have been alarmed when the rings seemed to come from a drawer of rings and not supplied as part of a piston set. So I bit the bullet and ordered a set of Wiseco forged Pistons from Cake St Classics which were promptly installed and all is good. Took it for a run today and no problems. Off to the National BSA rally next weekend in South Australia which should run it in nicely. Any one else going?

Mark