[mrmax]

David, you keep mentioning F1 motors while they are wonderous, they only are 3.5 liters (about 210 cubic inches). Pistons the size of maybe a 12 ounce soda can and most likely similar weight. Sure they spin up to 20k rpm but are not likely to produce stresses like 4.25 bore slug and rod combo. By the way nearly all superbike motors are inline 4 cyls. with exception of ducati and honda rc 51. Do you recall 2003 mustang cobra? Was supposed to be aluminium 4.6, block was at its limits with planned 400hp. Ford decided to nix aluminium and go with cast iron to avoid warranty claims from people who do such dastardly deeds as improve exhaust change pulleys etc. . As far as dyno time thats great but an engine dyno cannot accurately duplicate real world conditions thats why all major auto manufacturers have proving grounds. Put a finished motor in a car and thrash it like a customer might and see what happens after 50 or 60 k miles. I don't think this will be as easy or quick as most of us would like it to be. Also the 125 cubic inch motor in my kawi vulcan has a 4.125 bore and 5 inch stroke. It also is not sleeved kawaski engineers found piston speed to be such a problem they limited revs to 5250. it also is not a low perf motor 110hp 150ft lbs tq. This v configuration is a large consideration for side thrust loading in motors with big heavy rotating assemblies.