popping after letting off gas: please help

[beesbluebike]

hi i have a 2005 yz250f

it is ported polished

has a power now intake

and when i let off the gas it seems to pop bad

could this be a leak fromt h exhaust or is the jetting wrong

also when i sit in staging before a race ill let my bike warm up but my bike heats up and the pipe gets cherry red and all the other bikes are still cool

can someone tell me what to do

thanx

[Bill_P]

You're running lean. Most likely you need to adjust the pilot screw or go up a size on the pilot jet. See the jetting forum for instructions on how to do this if you don't know how. 4Strokes are NOT meant to sit and idle. The header glowing is normal and will be worse if you are runnning lean - which the popping indicates that you are. There is a chance that you have an air leak which would exacerbate your problem. Check the header, midpipe and manifold carb connections and make sure they are secure. bp

[Dwillrace]

If you forgot to put your hot start down tight on the carb it will pop alot when you let off the throttle because of the extra air induced. Somewhere you are sucking in extra air. It will also do that if your needle is lean a clip.

[tenis24]

My 04 used to pop until I installed, the JD jet kit. It was lean like they said, and it pops no more.

[zeppelin69]

if you already have the jetting dialed in for the most part (you know your pilot, needle and main are good) then all you need to do is adjust your fuel screw

[Matt96xr6]

check the pipe for air leaks

check the carb manifold for leaks

test the hotstart, lube and adjust

if you still have problems, go up to a 45 pilot