I am looking at a 99 Fatboy that I really like except for the fact that it has a stock 80 inch motor in it. How big could this motor be punched out to without modifying the cases? Machine shop work down here isn't the best and I'd rather just stroke the motor and put bigger cylinders and pistons on it without having to do any case mods.

 

89" is it without boring the spigot holes.(or unless custom length cylinders are used to accomadate a 4 3/4"-5" arm.)
Set up correctly, they can be mighty damn powerful.
Scott