Bandit backfire exhaust acceleration - 1997 Suzuki GSF 600 S Bandit

Hi Dion:
When under acceleration, an engine experiences increased cylinder pressures. If you have a spark plug(s) that is in poor condition, it can misfire (or not fire) then, so the unburned fuel will ignite in the exhaust, and "backfire".

Another possible cause could be that the timing is not retarding when the vacuum drops under acceleration.

My recommendation?
TIME FOR A TUNE UP
Cheerfuls.

Depending on make model and year, could be a valve problem or an ignition timing problem including the dist. cap.

make sure there isnt any thing in the air box or exhaust little critters like to nest in them

Pops and backfire on deceleration would normally point toward lean on fuel has it got after market exhaust or air filter ? these both will cause it to want/need more fuel
may need to fine tune fuel air mix

Backfiring on deceleration is air getting into the exhaust and igniting unburned fuel. You probably have an after market exhaust on. You need to seal up the exhaust system by replacing all the exhaust gaskets. Dig the copper crush washers out of the head and replace them with new copper crush washers. This should take care of most of the popping. If the problem persists,unbolt the fuel cut diaphragms from the side of the carburetors and inspect them for holes and stickiness. Replace the fuel cut diaphragms if they are bad . Fuel cut diaphragms are on almost all Honda Kei Hin carburetors to stop the cycles from popping or backfiring on deceleration With the stock exhaust.

Sounds like a vacuum leak in the motor. Backfiring may be its own problem altogether. Backfiring only occurs when cold air is being introduced into a hot exhaust stream or when the timing is off. Check for vacuum leaks under the hood and leaks in your exhaust. If you have a leak in your exhaust it could be interfearing with your emission sensors and giving your motor false information.

Are you talking about "backfiring" out the exhaust or "spitting back" through the carb?

Backfiring through the exhaust under acceleration is rare. If he ignition is misfiring, unburned fuel and air mixture is exhausted into the exhaust system. The next time the plug fires, it ignites this mixure. In other words, your engine is "missing" and your ignition system needs attention.

If it's "spitting back" out of the carb, this is usually an indication of a lean mixture. If it's doing it at wide open throttle, you might need to go up one size one your main jet. If it's doing it under less than full throttle acceleration, raise your needle up one notch and try it again. You want to richen the mixture just a bit. Too much and the bike will get sluggish.

Intake:
Lean, or spark control problem, valve problem, bad fuel, plugged carburetor.

Exhaust:
excessively lean or rich with exhaust leak, valve problem, spark control problem.

check for leaks around the exhaust headers,mine did what yours is doing,i replaced the copper exhaust seals in the head(exhaust ports),air is getting into your exhaust system and it mixes with the unburnt fuel and ignites causing the backfire,i replaced copper seals(about $2nz each) and problem went away

No not cdi - u r running super rich U need to rebuild carbs