I’m going to keep my 2005, 400EX all stock, but noticed when I tried some shorter tires how much more responsive it is. I really want to run the factory height tires for the ground clearance, but would like the gearing advantage that I got with the shorter tires Since it will not see too many top speed blasts I can live with the steeper gearing. Can someone recommend what works good in the number of teeth on the sprockets. can I get away with just changing the front by one tooth.

While I’m asking---I don’t suppose there is an aftermarket muffler that is quiet, but still gets a performance advantage over stock? I really like the quietness of this quad. Thanx, crossy

 

Nice to see someone who wants to keep quiet!!! LESS SOUND = MORE GROUND!

Muffler..check out the FMF PowerBomb Header and Q4 Muffler, EHS Racing airbox lid with Outerwears, and ProDesign (ProFlow) air filter. The Q will be louder than stock, but not near as loud as the average aftermarket muffler.

By putting on smaller tires, you lowered your effective gearing. You can look up your current gearing ration here, then judge what changing to different size sprockets will do: ATV Gear Ratio Chart

You are looking to gear DOWN, so you can either go smaller in front, or larger in back. 1 tooth in front = 3 teeth in back, so keep in mind that a small change in front is like a big change in back.

Here is my experience with the 400EX. I went to ITP XCT tires which are 22" in the rear, so I figured I needed to gear down. I went 1 tooth smaller in the back...and it was way to much! Any time I stabbed the throtle, the front end would reach for the sky. Great fun for playing around, but out on the trail it almost got me killed. Finally, I settled on 1 tooth larger in back as a good compromise.