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Jetting issues?

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2002 DRZ400s

FCR39 off yfz450


Yoshi rs-3

K&N air filter

elevation where i live is around 400ft but i regularly ride to sea level and sometimes above 400.
fuel screw is currently about half a turn out from fully seated.

Issues: Runs great in temperatures from 55F-75ishF but around 80-90F+ the bike seems less responsive, surges with constant throttle in 2nd and 3rd and pops when decelerating. bike is also more responsive after just starting compared to when i've ridden it for awhile and its warmed up.

had a problem where sometimes when coasting to a stop with the clutch pulled in or while idling at a stop the idle would drop and the bike would die. sometimes i could save it with a little throttle to bring the idle back up other times it would just die. adjusted the fuel screw, changed the spark plug, and rerouted the fuel line so it didn't have a loop in it and the problem went away for about two months until yesterday.

had it jetted at a shop awhile ago but I don't think they did it correctly and at this point i'd rather just do it myself. from the invoice i have it just says they put in a "kehin fcr needle" and a 160 main jet. havent opened up the carb yet to check as im waiting till i have the parts i need  incase i have to change whats in there

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Warmer weather causes richer running. Really need to know your current jetting. The DRZ is tolerate of a wide jetting range while not optimal, it still runs cleanly. You must already be
near the extreme. The FCR jetting in FAQ's should get you close enough to carburate cleanly. From there you can fine tune.

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