I've been ridin bikes for 15 years. I recently bought an 06 RMZ 250. My first 4t, been a 2t guy. The kid i bought it from said it needed carb work, so i cleaned the carb, put it back on and it did the same thing (wouldnt idle with choke off). So I dug a little deeper to find that the valves needed shimmed and needed a new timing chain and tensioner. Got all that put on. Runs great now except for the fact that it really backfires on decel. So i bought a JD jet kit for it, man its really comin to life!! BUT STILL POPPING ON DECELERATION. Is this a bad thing or am i making a mountain out of a mole hill?

You may have an air leak either where the exhaust heater mounts the the head or where the silencer and header slide together.

Other than tightening the header bolts how do i go about finding a leak?

Or your head pipe could have a crack in it.

Edited by Nyk745
missing word
Other than tightening the header bolts how do i go about finding a leak?

Start the bike when it is COLD and spray soapy water around the head pipe (look for bubbles). This would have to be a fast process because as soon as that pipe heats up your water will be evaporating. I would just throw a new gasket behind the head pipe and see if that helps. Also check the connection between the silencer and the head pipe.

Easiest way for me to check for an intake leak is to start it up and spray Carb cleaner around various spots, intake boot,ignition with cover removed etc.and listen foe an increase in idle.

I'd bet that you Just need to go up one size on Your pilot though. Usually popping on decel is a lean pilot circuit.

Good luck. Let us know if you resolve it what it turned out to be

I've sprayed carb cleaner around and nothin. You say with ignition cover removed? What do you mean by that? But i have sprayed enough of that crap that if it were gettin in it would have. I think its got a 35 in it but i also have a rocket pipe on it. Thats why i put the JD jet kit but it didn't come with a different size pilot. But i will definetly put my other header pipe on and see if that cures it and get a few pilot jets comin. Hopefully thats the problem.!!! Thanks alot guys!!

Late to the party here. If the bike is popping on decel... Have you tried the basic of just adjusting the air/fuel screw? Typically, that is all that needs to be done. If you're lucky.

Leaner or richer?

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