now back to your to your bogging problem,i cant say this enough times,reed valves will not run rite without a ported piston.i had the same problems with my gt80 in the begining.i must have went through every thread on this forum,studying,trying to fix it.i tuned and tuned,then some more,untill i came up with the tune thats on it now.now im going to try a set of main jets,these motors are not a tune once and forget ,to get and keep running rite takes tuneing.im saying this with over 1300 miles of expereance with the exact same motor,ported piston,a good x pipe will help a lot.go online and look ported pistons,make sure you order the rite one as there are two types of pistons,a type a, and a type b.on one of them the hole for the wrist pin is higher than the other,or you can use a dremmel tool to port your own,