Would all years of pipes fit the 04 400ex. I know the changed alot on it and was wonderin if that was one of them. I just bought a HMF slip on and it never said what year it is for. Any help would be great. Thanks

 

Any pipe made for a 400EX will fit any year.

 

Thanks. Will it hurt the 4 wheeler to run a aftermarket pipe on it without havein andthing else done to it.

 

With a HMF, you will need to rejet the carb. If not, you could possibly damage the motor by running to lean of a mixture and besides, you won't get hardly any performance gain if you don't.
I had an 04 400EX and loved the quad. I had a Pro Circuit slip on and it done really well. If I had to do it again though I would go with HMF. Thats what I'm running on my Raptor............... [img]i/expressions/face-icon-small-smile.gif[/img]

 

Yea i looked at ur pics. How much horsepower do u think it will gain if i got a k&n power kit to go with the HMF slip on. Thanks for all ur help

 

Not sure, but you do need to do the combustion chamber from both sides (intake and exhaust) to make any mods effective.