what can I do to a 400ex

[Reggie44]

What's the best I can build a 400ex and still run pump gas

[86 Quad R]

i've had good results by reworking the ports, a cam(type depends on riding style), slightly bumping the compression up to about 10.5/11.0 and a good exhaust.

[gojk]

I have a 416 at 11:1 with the old style hotcams stage 2 and it runs really good.

[rooster300ex]

U can do build it however u want. Just don't go over 11:1 compression so u can still run pump gas.

[bcapien]

If you look below you can see everything i have done to my bike.. It runs great and has lots of power.. I can still run pump gas but i prefer to just run 94 and add a bottle of octane boost..

[speedfreek]

You can port the head! Send it to me for this. P.M. me if interrested.

[riggsracin]

exhaust, jetting, shave the head, tune up. shave the fly wheel. pm for free estimate i see ur in ky also