I have a 1976 R75/6 that has been modified with larger cylinders and pistons, 40 mm Bing carbs and twin plug heads. I was told the cylinders and pistons are 1000cc. Is there an easy way to check the size of the cylinders?
I was reluctant to respond initially since this question is beyond my range of knowledge. While there may be a proof mark that is specific to the cylinder's displacement, I don't know that for sure. You could determine the cylinder displacement by measuring the bore, but that would require a partial disassembly of the motor. I would guess that the motor has been built up to 1000 cc's due to the 40mm carburetors.
former Airmarshal, IL.