2005/Suzuki/RMZ250 Elevation about 850 Temp 30-50F humid or dry conditions Main 185 Pilot 42 Fuel screw 1 3/4 turns out Starts fairly easy but won't stay running when the choke is in. Backfires and sputters when I keep the rev up (to keep it from dying). Fire comes from the pipe when we don't use the choke. Even holding the choke part way out makes it run better. I took the carb apart, removed and blew out all the jets as I've done before with other Keihin's I have had. We cleaned the air filter and installed a new plug. I also cleaned out the hot start, and replaced the cable and ends. Those things made little difference. This thing just seems to not be getting enough gas. Given the 42/185 jets, how could this be? I think they are substantially bigger than stock. William1 and Burned, do you have any suggestions for me?