Pw80 tuning

[Offroadindaddy]

My 7 year old son mowed lawns and save his money to buy a 2006 pw80. He is short so he can't go to a bigger bike yet. He left bed it but would like it to go to its full rpm. When he rides he said he can faster at 3/4 throttle rather than full. It seems to bogg and smoke more it full throttle. I am open to any and all suggestions. I am an airplane tech but don't know two stroke running much. Also anyone have experience with the black dragon mods on a pw80?
Thanks
Steve