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RM-Z 250 Carb tuning

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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?

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If you had the carb apart make sure you put it back together right. I've read countless posts where the plate was put it in upside down and now the bike only runs with the choke out!

"the square end should be down on that thin plate that goes on the head side of the slide"

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