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new backfiring and popping noise

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After my yzf exhaust upgrade I dropped the needle clip to clean up the bog..worked great(was in the 80's no moisture in the air)..only this weekend with temps down to low 60's and humid it pops and spits some flame with deceleration. Should I move the clip back or is this a fuel screw adjustment now?

thanks

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Cooler air is more dense, so you should be a little leaner when it's cool. You should be able to fix it by opening your fuel screw in 1/4 turn increments.

Seems like a big change though for only a 20 degree temp change. Could you have some kind of air leak?

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An often overlooked, and very common cause of decel backfiring is an air leak in the exhaust system. A lot of the aftermarket systems use a simple slip fit between the head and mid pipes in place of the clamped and sealed joint the OEM system has. I can make my son's bike pop for you anytime I want by loosening this joint. Mine has a slip fit and pops a little most of the time. The leak can also be at the head. A little fuel and plenty of heat are normally present in the exhaust anyway. Ad air, and it goes bang.

A lot has been said to suggest that lean idle mix is the only cause of this, but if you fatten the fuel screw to stop the pop, don't be surprised if the bike seems to run rich.

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