Popping noise when I let off throttle

[baywatch7737]

Ok guys I'm kinda worried. I'm running a tgb 101s/keywest with malossi sport 70, technigas pipe and carbon fiber Reed valves. Also I got a jog keihin carburetor on it. I'm running a 90 mj with the stock air box with 4 3/8 holes drilled. When I let off the throttle when I'm going fast ex 40 I get some pretty loud popping noise. Not sure where it's coming from as it's hard to tell while riding. Looked around and came to the conclusion that my idle jet is a bit lean for this application because when I let off the throttle at high speeds it's still getting a lot of air and not as much gas.

I have tried turning up the fuel mix with screw, covering various holes on air box and raising needle back to it's original position in the middle. But I run to Rich and bog on my start before I can find the perfect medium. I looked on jets r us to try and find pilot jets for this carb and I couldn't find one with this one's exact dimensions.

First thing, what is this popping noise, and how can I fix it?

If I should try a new bigger pilot jet where can I get them or does anyone know if some of the different ones on jetsrus will work? Another thing is I wouldn't even know where to start with pilot jets because the one that came in this knock off carb wasn't labeled.

[jeff84]

its nothing to worry about really. even the best tuned carb will pop when the throttle gets slammed shut at high rpm. its the nature of the beast.

[jeff84]

the only real way to get rid of it is to rum a better muffler, which usually means non performance pipe

[gsx600racer]

I would check the exhaust for cracks or leaks. Fresh are entering the hot exhaust will tend ignite any unburnt fuel that's still in the exhaust.

[jeff84]

yeah, that is true, but lots of carbed motors do this even when there is nothing wrong. 4 strokes with emission heads do it by design but it isn't noticeable until you get an exhaust with less sound dampening. that is the only reason I blocked off the pair valve on my 4 strokes.

[repherence2]

check the torque on your head studs/nuts. 1 stud might be loose.

[bendover]

On 4 strokes, this is a classic sign of one of the jets (forgot which one) is too lean or too rich (forgot which). Maybe it is the same. Try your luck google it, classic symptom I think. I have same on my motorcycle. Harmless I was told (note: 4 stroke!)