Ok, i 'assume' my bike is 4 stroking above 75% of throttle. Great pick up across the power band until i hit 65-75% of throttle. The sound changes like its missing every other stroke and the acceleration stops. Heres the deal..gas flow is fine, high performance air filter breathes great, no intake leak from the brake cleaner test, needle set on second notch from the top, spark plus is nice chocolate brown with no oil or white burns, exhaust is modified slightly and flows fine, 100 total miles on engine and using 40:1 synthetic oil.. now what in the world could cause my problem. Its still fun to ride and never fails to idle, start or run. Just wish i could figure out the high end problem to get over 23-25 miles an hour. Thx for reading this guys, any help is appreciated.