i am getting a mikuni 160 mian jet for my z400. i have a K&N air filter, and yoshimura slip on. my elevation is 656ft. on the fuel adjustment screw, how many turns out should i do? dynojet says 3.5 turns below 5000 feet, would that be the hold true for the mikuni 160 jet also?

 

The number of turns is just a starting point. Things like humidity and temperature, and altitude change the mixture, too.
Theres a procedure for adjusting the mixture screw in this article on jetting. Motorcycle and atv carbs are basicly the same, and in some cases are totally identicle.The tuning is the same on both.
The mixture screw will have no effect on carburation after 1/4 throttle, it effects the mixture at idle.

jetting

 

so, if it doesnt idle right play with that?

 

Right, ...the mixture screw effects the mixture strength, and use the idle speed adjust to get the correct rpms. The main and needle circuits wont effect the idle, in fact, you could totally remove the main jet, and it will still idle.