It seems that during overhaul engines and gearboxes were sometimes painted green; I have such carter, apparently painted with a 4" brush, and the match marks are not visible anymore. I suppose the engines were assembled with matching halves, but on the magdyno platform there is about .4 mm difference; the flywheel turns around without any problems or grinding noises. Question: can I use it with a shim under the magdyno?
Normally shiming is not a problem, but 4 mm ? That's a lot.
If there is such a difference, Hans, it's probably not a matching pair.
Maybe you should check the marks under the paint.
As BSA crank cases had the main bearing housings and the 'register' (the lip and recess at the crank case joint) machined in one operation, as long as the fit there is good the main bearings will be in alignment...
For that reason running unmatched crank case halves doesn't present any problems mechanically...Slight discrepancies between the mag platform surfaces and/or the barrel mounting faces are sometimes seen and either a light skim of the faces on a milling machine or, in the case of the mag platform, the fitment of a shim can successfully address this aspect of the job....
I've run 'odd halves' a number of times and know of one BSA that has competed in the Manx TT at least 3 times in such a format!....Ian
