Hi my name is Les, I have been trying to research my bike for quite a while. If anyone has some input please comment. my engine is Frankensteined together. My cylinders are S&S 124" and heads are 120R screamin eagle. The crank case is original, bit in order to make this work the crank case had to be modified. I am trying to find out how a crank case can be modified to accept different rods (ie: bigger diameter piston and/or different rod). If I can understand how to modify a crank case maybe i can understand how my engine was built.