1. Centering the crank
As we have rebuilt a new crank around the old flywheel and are using new crankcase halves and new bearings, it is necessary to shim the crank to give it the appropriate endfloat and ensure it is centered. To do this we checked the old main bearings against the new and found them to be exactly the same size (width). We then spun the old bearings up on the lathe and relieved the centres with emery paper so they slipped on and off the crankshaft easily. We pressed the old bearings into the crankcases and bolted up the crankcase halves with the flywheel inside. The old bearings allowed the crankshaft to be pushed backwards and forwards to measure endfloat and the centre point. The CZ 175 flywheels run extremely close to the crankcase in the mouth and clearance between each side can be measured with a feeler gauge. By this method we inserted shims to centre the flywheel and left enough for a reasonable degree of endfloat. Once we had balanced each side we set the endfloat at .0008". Then it was simply a matter of popping out the old bearings, in with the new and double-checking the clearances with the feeler gauge. Perfect.