I'm planning to be in the US early next year and hopefully will get a chance to start putting my P11 together as early as late February. I'm building the engine with JSM Carillo long rods, lightweight pistons, JSM cam and followers, other stuff I can't remember off the top of my head. Motorson from this site will be helping me (instructing me? I've built dozens of japanese engines, but never a british one!) and once it's running we'll see how it vibrates compared to his Commando. I know crank balance factor depends a lot on what rpm the engine is intended to be used at, anybody got any recommendations on the best balance factor for a JSM equipped P11 engine? I really should just ask Jim, I'm sure he has a recommendation.