GT Thunder rear link has not busted the bottom out of the air box has it and getting water seen it done by a guy one time lol
Joseph Wilkins ATV B VET #349 2010 Sponsors EKS X Brand Goggles, Physco Wear,Maximum cycle racing,Powermadd,GT Thunder,Kenda Tire,DP Brakes,Regina Chains
Several possibilities, but you might check your needle position. Your needle and main jet control from quarter throttle and up. Sounds like it may be set too high(raised,let's gas flow sooner from main), which would cause a rich spot starting about quarter throttle-causing a bog or sputtering. Once you are at full throttle, you're pretty much running on nothing but main jet, so the misadjusted needle has little or no effect.
That's my SWAG, based on the little bit of info. Good luck! (:
"While any other may stand and talk, the Walking Man walks."- James Taylor
jeremy, joey is right about the link. it happened to me right before jakes race this year. but if you have a basic engine not highly built the jetting i would recommend is 185 main, 2 1/2 turns out on the air/fuel screw, remove lid or get an hrc lid, and an hrc needle on the 3rd (middle position). those jetting numbers should be so close you cant tell much of a problem. if it has ever had a dyno jet kit in it have fun. i can give you some details on that.
did you get a sparks needle that came with the exhaust? if not i would call or email them and ask them their recommendations.
im will bet the settings i recommended will get you close. the airbox thing check unless you have the lid off already.
no gt link .....416 im runing that excact setup but im using the sparks needle only mods r sparks big core pipe sparks air filter kit and the sparks jet kit and stage 2 hotcams,,, im done wit it,, its spencer headach now
if it ever had a dyno jet kit in it there is an air circuit in the air horn is more than likely plugged. drop it down to a 165 main and it should be just spot on. i had the same issue with mine. a dummy put that kit in it right before i purchased it. i liked to have never figured the jetting out