Backfire issue HELP!

[JolleyBinks]

Hey guys... I have a 91' CBR 600, fixed the problem with the gas leak and now I have the bike starting fine and running. However, when i really wined it out at high RPM and then let off the throttle I get a heavy backfire when the engine revs down and throttle is completely taken off ... this happens only under stress not when the bike is at idle and revved high then let go.

Is the a common problem that can be fixed by and armature.
I have 3 ideas ...

Carb adjustment
Ignition Timing
Running lean

Any suggestions I will really appreciate.
Thanks for your help

Binks

[Stoneman]

Is the a common problem that can be fixed by and armature.
I have 3 ideas ...

Carb adjustment
Ignition Timing
Running lean

Carb adjustment & running lean is really 1 idea...

But yeah, I'd say it's carbs. My guess is the backfiring is unburnt fuel...

[Rambunctous]

Exhaust leak okay? Check if your idle jet(s) are clogged.

[DuncanMoto]

Wirelessly posted (BlackBerry9000/4.6.0.297 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/102)

1st clean out all jets.
Check spark plugs.
Check timing.

[butcher bergs]

If it backfires after a couple seconds once the gas is let off the you're likely running rich.

If it backfires pretty much right away once the gas is let off you're likely running lean.