Last night I was riding for some odd 3 hours on my friends farm. Nearing the end of our riding time i took it down the road and opened it all the way up.. in 5th it sort of bogged out on the top end but i pumped the throttle and it seemed to get better. In 6th i was going WOT for about 2 or so minutes and then i hit the powerband unexpectedly.. how come its not always there? what could be wrong? what are some things to check? BTW its 100% stock internally.