The trx 90, goes about 30, if you where to put a pipe,jets,and K&n AirFilter, how much more Mph whould that give it, please i really want to know.

 

If you want more top end, you are going to need to change the gearing. Adding power will help then. Stock gearing seems to be the limitimg factor here.

 

Ok, thanks but how do you change your gears????

 

You need to change the sprockets, nothing with the tranny. Bigger front sprocket or smaller rear sprocket. For wht it is worth, I think it is geared pretty well stock. Maybe after you get that motor built up, going up 1 tooth in the front will do ya.

 

ok, thanks alot dude, but what do you mean"when you bild the engine up", like bord it out to the 125cc???