Hola, first post in thumpertalk. I just bought my first Dirt bike, a brand new 05 yz450f. I was hoping I could get a few questions cleared up.. 1. When letting off the throttle the rear exhaust tends to make a popping sound. Bike makes no popping or back fires when I am on the throttle. From what i have read on the site you all say its either exhaust leak or Lean setting.. I have removed the rear exhaust slip on once.. but the bike popped even before I removed it. Most ppl say to turn the air screw 1/4 to 1/2.. What direction? ( clock or counter clockwise ) And Where is the air screw loacted on my carb. I will look in my book once more to see if I can find it. Is the popping bad for the motor or just annoying to the rider. 2. Also looking to pick up some Pro Taper bars tommorow. the stock bars are annoyingly to low and wide.. Will the new bars fit in the stock clamp, And How much of a pain is it to remove all the leaver parts and such and reinstall to the new bar.. Will i need to replace my grips? 3. Bike settings.. I dont know rebound settings from race sag.. I was hoping someone could clue me in on a set up for a person 190lbs looking to do mostly aggrestive trail riding with some lil jumps involved. I will have the dealer setup the bike when i take it in for the break in check up.