crf450 carb issues

[brian350rx]

On my new hybrid the motor has a 488 piston, stage 2 cam, ...... 175 main,.....
It runs really well with the choke on (stock carb from 03) but with the choke off it pops and cracks and wont stay running
Anyone have any advice?

[duneflyer1]

sounds like you are WAY lean... bigger jet like 4 sizes

[loboboy]

check and make sure your fuel mixture screw has not fallen out. A freind of mine lost his mixture screw and it did the same thing yours is doing.

But if the screw is in plcae then you need a much larger pilot jet and probably a bigger main jet.