02 Bandit 1200 backfiring problem

[cudagee]

Hello everyone, hope someone can help
I have 2002 Bandit 1200 and I am having a backfiring off idle from the carbs upon take off
I replaced the spark plugs
The firing order is correct as far as spark plug wires
I know its ignition missfire
I it sounds like timing is retarded, but I don't know if there is any adjustment
Thank you in advance,
John

[kwaynee20]

Ever had the carbs cleaned? If not that could cause the mis fire. If you've had any upgrades recently it could also be an air/fuel mixture problem.

Thanks for the reply
No I never did anything with carbs
When you say carbs do you think I need to get jetted or just idle mixture adjustment
It looks like it is sealed do I have to drill out the plugs to adjust the mixture?
Thank you,
John

[RatBike]

When did the problem start ie what changed?

Hi, I actually bought the bike like that. The bike wasn't driven for only 3 months. When I got it the first thing I did is drain the tank and fill with fresh gas. I don't know how it drove before that
John

[RatBike]

3 months isn't really long enough for gas to go bad. Regardless how much fresh fuel have you run through it? Backfiring back out the carbs did you say? That wouldn't be caused by retarded timing. Is it on every cylinder or just 1? What does it do when you run the piss out of it? Knowing how it ran before it was stored would be very helpful. If one of your intake valves is sticking partially open you could be in for some trouble. If it's blowing back through several of the carbs you probably don't have to worry about valves. Mixture problems usually will cause a back fire through the exhaust. Now I'm rambling aimlessly. Need more information.

I already have driven it with 4 fresh full tanks
When I get on it it great no problems
The only time it backfires from the carb/intake is when I first accelerate from a stop light or if I am sitting in idle and I twist the throttle slowly. It sound like maybe just one cylinder. It does not backfire through the exhaust at all

[RatBike]

You should log in so that your posts are linked to your profile. This is a stumper. I don't think it's pre ignition because the condition would get worse when you're on the throttle. You said you thought it was retarded, but for the mixture to still be burning after the intake valve opens? Nope. If your jets were plugged in one carb and it was running extremely lean it could get so hot that as soon as the mixture starts entering the cylinder it could light before the intake valve is closed blowing fire out the carb. Check the header temp after it blubbers at idle for a while to see if they're all about the same. I think you probably just need to clean out the jets. Hopefully you don't burn a piston in the mean time.

[cudagee]

Thanks I'll clean the carburators
John

[RatBike]

Originally Posted by cudagee Thanks I'll clean the carburators John

Know how?

[CJ2K]

The first one was moved to the appropriate section. Why would you post it again. This doesn't belong in here. Please look before posting. Thanks.