I just bought 2002 a 400ex. I added a E-Series slip on and a K&N in box filter,,, Should I jet it up??? What else can I do to wake this thing up. Keep in mind I am on a tight budget, Mostly looking for jetting tips to match the pipe and filter application.

Thanks to all!!

 

Go up two sizes on the main jet. Buy you a WB rev limiter, higher compression piston, and put a xr400 cam in it. That should wake it up some. A friend of mine I ride with did this set up and he is very pleased with it. When I rode it pulled alot stronger than my stock 400. It should also be a relatively cheap project compared to what you could do to it. Good Luck.

 

Thank you , Sounds like good advise to me.

Thanks again!