GSX600F Backfire

[Benjie]

Good after noon i am working on a GSX600F a guy broth it to my shop to clean carbs . said that it didnt start because they might need cleaning. so i cleaned them and tryed starting the bike and wouldnt start. 5 secons later after letting starter botton go there was one big bang. so i checked the spark and i see it has week spark but after starting it always sparks one last time 5 secons later. could some one tell me what to look for

[maniac1886]

How did you clean the carbs?

Check voltage at the coils. Should be at LEAST 11v with the bike on (I don't remember if its supposed to while cranking or not) weak spark can come from under powered or weakened/failing coils. The big wham makes me feel like it's a carb problem tho.

[Kreylyn]

Double check the coils have the correct wires plugged to them, and the proper order for which coils go to which set of plugs. Left is 1-4, right is 2-3.

Krey

[Benjie]

GSX600F Backfire

Cleaned the carbs with carb cleaner done thousands of bikes already . Just this one i am confused with that it would backfire 5 sacons after letting the starter button go. I i put a screwdriver in the 1 and 4 spark plug cap they have good spark but 2 and 3 are week and after 5 sacons you see it lets go a spark again even if your not cranking the engine . any body could tell me if the ignitior is faulty

[Mrontime]

Does it do it to another plug if you swap the coil in puts?

[92xjunker]

Wiring issue to the coils, specifically the coil feed. I would not eliminate the igniter box..sounds like capacitive discharge is firing the coils.