poopstick

You need to degree your motor on all the ports, where the exhaust opens and when the transfers open, port timing can make a good motor or a pos! I have seen so many cylinders ruined by porting, no matter what you do it's junk.

Nasty is correct on the 100ll, it will work but not a good idea for a banshee, Your quad is not an airplane the 100 octane is inviting but the motor you have you need to convert it to pump gas any way its not built to make power why run all that compression just stressing on crank parts, there is a de-icer do to altitude I believe.

yes getting a perfect pipe to help this is hard, pipes are made by alot of people to make money, now I know Matt does alot of work to get his pipes to have a better power across the band, to say look my bike made 90 HP on the dyno and then just fell off is useless,

if you go BB you need to increase the port size by the same percentage, on stroke you need to measure piston speed by feet traveled per minute, so if you run a big stroke you need to back down the RPM's, on the port measuring there you are on to something but most don't bother, a sweeping transfer (Honda) is ideal not the 90 our banshees have but Yamaha did not intend for this motor to get this out of hand, port timing back angles mean so much and everytime I see that kfnife edged intake I wanna throw up! so can a good builder take a BB stk stroke and just kill a 4 mil stroker you betcha