Re: Knucklehead 74'' pistons!
Lower compression will equal longer bottom end life, so with that if you go to higher compression how often will you be running at 4,000 RPMs and higher, racing or just plain running the bike hard?
The more often you run the engine hard the shorter the life.
It is safe to run the pistons but how long will the bottom end last?
You did not mention what year the cases are and if you have 40 or earlier I would not run anything higher compression as the short rib cases are more prone to cracking along the spigot area of the cases due to added HP and torque.
NEEDED, bull neck frame for my son's 47 knucklehead project.