We just built and old school motocross quad for the production lite class. It's a 1987 Honda 250X. The jetting on the machine is driving us nuts we just can't seem to get it right. The motor has a TC Racing head ported and polished, TC Racing Cam, Advanced Machine decked the head, 13:5 to 1 Custom piston, bored .080 over, Webb rockers. a uni air filter in a custom air box with no lid, We are also using air scoops, a external oil cooler and race gas to keep it running a lil' cooler. Usualy on the 300ex motors we've done in the past we'll use a stock 400ex carb with no choke and it usually runs mint but it's not panning out on this machine. We've played with a stock 300ex carb on this quad too but nothing seems to be working right. I'm thinking of putting a brand new 37mm flat slide FCR carb on it and giving that a wirl. Anyone have any ideas what I should use for a carb and what jetting I should use ???

 

Bump

 

i was using a 138 - 142 main on stock 300 carb for almost the same setup, couldn't get the 400 carb w/ no choke running right either so i gave up on it

 

We are changing the stroke in the motor in a week or so with a Powroll crank. It should come out to a 299 when we are done. So I'll try the Kehin 37mm FCR Flatslide on it after it's all done.

 

We are changing the stroke in the motor in a week or so with a Powroll crank. It should come out to a 299 when we are done. So I'll try the Kehin 37mm FCR Flatslide on it after it's all done.

 

should be 352 shouldn't it.. after the 12.7 stroker and 80mm piston