Hi All. I was looking at fitting a 900 crank to my S4 for some additional stroke. If I go for a pre ie (carbed M900 crank) will I run into charging problems as the 900 crank has fewer splines so I think I would need to change to the M900 carb charging system? Thanks very much.
I think you will have bigger problems than just charging. The carbed bike crank is quite different and won't take the 3-phase alternator. The single phase engine uses a different alternator cover and crankcases, all of which you would need to change to fit an (inferior) alternator. There are probably other differences too.
I suspected so. I'm not sure its really worth it for a few extra CC's. I have just have the motor on the bench currently and its just about ready to assemble (still a crank main bearing to fit) and thought id change the crank whilst it was apart for a little more stroke and cc's for very little money. I'll go with my existing crank then. Saves a lot of hassle all round by the looks of it. Thanks Derek - I appreciate the input.
