I have a honda 400ex 2002 i want more power out of it. I don't want to do a 440 bore but maybe a 416 or 426. can anyone help me on what i should do to it where i can still trail ride with it. an i drag race it so far it has a wb e series slip on, k&n air filter an jetted

 

416

 

If your wanting more power you don't nessecarily have to bore it out.

Thought about upgrading to a 450? May be just as cheap for the money you'd spend on motor work, depending what all you want.

 

My buddy did the 440 and he rides all the trails I do including the Paiute Trail in Utah..
;0)

 

An easy, cost free mod I did was remove the lid on the air filter box to gain a little more power, it increases airflow so the throttle is a lot more responsive and quicker. Sounds better too.