can anyone tell me what GOOD mods there are and what is worth it but not ones that completly take the quality out of the atv ( exhaust) '02 400ex !! THX

 

I like the mods I've done to mine so far. (see my sig) One of the best I've done was to drop 1 tooth on the front sprocket. (14 tooth) That made a whole new machine out of it. I like my pipe, but it is LOUD!! Something a little quiter would be nice. I haven't changed anything inside my motor (except the cam) so it should be as reliable as can be. (all bolt on mods) It will never beat 450's, but I really like my 400 and its still alot of fun.

 

does changing to a 14 tooth make the performance any better! and where did u get the sprocket at? also what exhaust would u reccoment thats a slip on that no TOO loud haha lik urs! thx for the info

 

Droping a tooth on the front makes it quicker. You loose some top speed but it helps down low. I can bring the front end up easly when trail riding with a blip of the throttle.
As far as pipes. I read alot of different forumns about this, but ended up getting my HMF because of the deal I got. Most people agree that it is a good slip on pipe. But it is LOUD!! I'm geussing over 100 db easy. They do make a quite core for it, but I really don't know how much they are and how the effect things. (sound and power) WB, Supertrapp, FMF all make good slip ons as well and some are adjustable. (there are also alot of others out there that are also as good)
One of the next things I do to mine is get some better front shocks. With my fat butt, riding hard, mine tend to heat up and bottom out alot!! Other than that, I think I've got a nice quad that should last me a long time.

 

SWEET!! so where can u get it at a dealership? yea i am looking to invest in a good and sound exhaust and also some ELKA front shox!! thx for ur 2bits

 

Yea your local dealer should have it or at least be able to get it for you. If not, places like Rocky Mountain has them.
Good luck!!