Motorcycle Repair: Bogging down, not enough power, yamaha wolverine, model yamaha

Question
Dear Collin, Thanks for your time. I have a 96 model Yamaha Wolverine. I am experiencing that mostly in my higher gears(mainly 3,4,5 gears) my four wheeler is bogging down on me. I have done the following: Rebuilt top half engine; replaced stator; replaced CDI box; replaced voltage regulator. The 4 wheeler seems to run, start, and idle well it just dont wind out like it should. The 4 wheeler will not really accelerate in gears 4 and 5. Ihave had other people to ride this 4 wheeler and they seem to think it runs at half force. I appreciate any advice you may have for me, thanks in advance, Andy

Answer
I hate 2 say this my friend, but your questions is way 2 advanced for me to answer over the net.  I need the bike to diagnos this issue.  I'll try to help though by asking, Why did u replace all of the parts u listed?  Why did u rebuild the top half of your engine?