I noticed that when I train to wheelie in first , after a few tries the throttle becomes slightly less responsive as the engine gets hot and it seems harder to get the wheel up when revving up the engine. The same phenomenon happens when I ride hard on fast trails . I must say I never ride with a full tank and I was close to reserve the one time I noticed a real lack of response after a few wheelie attempts. But the throttle response seems best when the bike is used on the road (for its regular use) and not too hot. I guess this can be said of all bikes when they get too hot. I just want to make sure my jetting is not too lean and needs to be fine tuned (the stuff in the exhaust is brown not very greasy) I believe it is stock, everything else is stock. But now that I think of it this engine is "kind of slow" to react to a progressive acceleration compared to my previous bike (YZ 250 2strokes). I sometimes would like a meaner engine.