Found this on another site! TRX450R Tire Size / Sprocket Change Calculator

[kazpr]

http://www.kg4vpv.com/~ncliborne/450r.htm

[markeg192]

I think I saw where Gabe made one of those. Pretty cool isn't it?

[MotoMom17]

alright, do it this way...read your owner's manual to find out how to adjust the chain to loose it to take you sproket off...blah, blah, blah...

get 18" tires, go from 14 to a aftermarket 15 sproket front tooth. that's what i did on mine and it is great. but the bottom end boggs down and doesn't give you a full powerload. a slip on will solve that problem. i just purchased a LRD slip-on that is overnight shipped to come in Friday. can't wait to get it jetted for racing this weekend. isn't this crazy? 118 stock jet. 125 with the slip on. 1freakign80! 180 with the airbox lid off. that's nuts going up 55. anyway, i'm sure that will give you a substansial power increase. i also use Klotz Nitro. it prevents knocks, preignition, and uses a cooling substance to keep heat and friction down. it is a higher octane, but it also improves throttle response, doesn't bog down in corners, and increase horsepower. it doesn't damage your engine but you have to rejet 3-4 jets up which means slip on, no box lid, and nitropropane i'll be running a 192 main jet. 6 1/2 hp increase throughout the powerband. with the nitro, jets, shoudl bring it to about 10. from 42-about 52. over the winter i'm rebuilding it (piston, cam, adjust valves) axle, a-arms, derisi rebuilt, triple rate shocks. the 450R is a great quad but definitly is not race ready. needs a slip on, nerfs, rejet, tires, beadlocks, and a few other things.