Its a 05 yammah YFZ450 with alot of upgrades. But the probelm is every time i leave off the throttle it will start popping. Not sure what could be the promble, need some help.

Thanks

 

Welcome to the forums. What type of upgrades? I can tell you your getting to much air and not enough fuel. You may need to adjust the air/fuel mixture or re-jet depending on your upgrades.

 

It has an HMF full exhaust and has some motor work done to it. I order a gasket from the head to the pipe. But if thats not the promble i will try what you were re-jeting it. But thanks for the help and the welcome to the forums.

 

I'm trying to understand what you are saying here but, you ordered a gasket from the head to the pipe? If that doughnut gasket as we always called it is causing an exhaust leak that will most definitely cause your problem. If it has a pipe on it hopefully it as been re-jeted.

 

usually you can fix this by making the fuel screw richer and/or going up a bit on the pilot. Make sure you don't have any intake/exhaust leaks first though. mine would do this from an intermittent exhaust leak.