Camshaft woodruff key sizes. I have a 1974 R90 with a nutty history, another story, and the camshaft needed to come out because the PO used brute force when over tightening the small nut holding the advance unit on. He broke off the end. The cam I removed has a much larger keyway, maybe 25% longer, than the camshaft I thought I would use to replace it. And of course the woodruff key is larger both in length and just slightly wider. I think later in the airhead engines they did away with the key and the end of the cam is slotted. My question is how do I find a cam that will fit? What years did they use different keyways?