What jetting would be right for my buddies 400ex with stage 2 cam, alba slip on, wiseco 10:1 piston, k&n filter, and no air box lid?

 

I'd start in the 160 range.

 

Thanks. He was referring to my bike. I ordered all the stuff on my parts list below in my signiture, and they are starting to arrive. So I should be putting it together this weekend, and was wondering what jet's I would need.

 

The HMF website recommends a 175main jet for their slip on, so that's what we are going to use.

 

i would probally start around 162 or so. this is keihin jets, not dynojets. however, jetting will depend on temperature and elevation levels too. hmf's jetting specs are too big. going with a 170 or larger would definately hurt your power unless your built pretty heavily.