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Hi all...what a great forum has proved to be very helpful..I just purchased a 93 dr650 goes great took it in 4 service...mechanic says problem with popping on deceleration!! he tried to fix by adjusting the air fuel mix but says that the little screw thingy beneath the carb appears to be stuck and unable to move??? believes to be corrosion or something says he may be able to fix cost abt 500 aud..anyone else had this problem?? cheers

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I believe he's refering to the air mixture screw for the idle circut. The engine can have the richness it needs while on the main jet but back off on the throttle abruptly and now if its running on a leaned out idle circut it will pop or backfire. Richening it up by backing the screw out will help. If its stuck spray it with WD40 and placing a small screw driver into the slot,(make sure the blade fills the slot to keep from tearing it up), "gently" and repeatedely tap the bottom of the screwdriver to send a vibration into the screw that with may luck loosen it. Be very careful and patient though because they made the carb out of some seriously soft metal.

Once you get it loose turn it in "gently" then back it out 2&1/2 turns(stock is 1&1/2). If this doesn't work go 3&1/2 tops. But before you go over 3 turns there may be something else going on. Check for and exhaust leak say at the head or mid way back where the head pipe meets the muffler. You'll see signs of blow by. If thats the case seal it up with permatex copper plus sealant. If the exhaust sucks air when decelerating it will backfire bigtime.

:thinking:It may be a good idea to check for the exhaust leak first. If thats the problem you won't have to mess with the carb.

Mike.

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Great...thanx very much 4 ur advise..will get back to the mechanic armed with yr advise..cheers stiz.

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