"Chirping" Backfire?? (video)

[kcoop99]

Ok, so Mark and I seemed to get everything going just fine (carb sync) and all was well, I didn't touch anything else and then I was getting a slight backfire at idle or deceleration. You can hear early and several times in this short video the "chirping" that will sometimes kill the bike as well as the backfire. Thanks for the help!
http://www.youtube.com/watch?v=2psiyqD3gSg&feature=youtu.be

 

[ZackDaniels]

Sounds like a bit of a ping to me. Pull the plugs and check if they're telling of pre-ignition.

If you've modded the bike a bunch or live in an odd altitude it may need more than regular octane gas if you're rolling with that.

 

[kcoop99]

It is almost like air is getting cut off or something. Hell, I don't know! There have been no new mods or anything and I run 91 octane....could the gas be a problem?

 

[NHVmaxpower]

sounds like a plug fouling out to me jmo

 

[maleko89]

Kyle, that's a carb backfire to me. I think the best thing would be for me to go through the carbs and give them a good cleaning. It's been a few years.

For now, check plugs and look for pre-ignition. You'll see specs if the mixture is pre-igniting. At worst, the electrodes will deform. What gas do you use? I always used 87 non-ethanol. Might be time for some BG 44K to clean out combustion chamber.

 

[mr.maxx]

yep def a carb fart.....

 

[davesax36]

It sounds like what mine did....

http://www.youtube.com/watch?v=mxb4euGQlP4

My carbs were totally messed up, but from what I understand, that could be from clogged pilot jets. Do the pea shooter and the shotgun and you might have good luck. Does turning your a/f screws change anything?

 

[Rusty McNeil]

I agree it's for sure a carb fart/intake backfire. That tries to reverse rotation on the engine and will sometimes kill it.

I Notice your bike was cold at that time. I bet it gets better when it's warmed up?
Does it also do it when you barely move the throttle off idle when riding cold?

My bike will do that when cold if theidle screw set too lean, gets better when warm.

If you think the carbs are in good shape and clean I would Richen up your a/f screws some and see what happens.

If A/f is too lean when you blip the throttle slightly the rpm's will rise and then slowly return to idle set point. If a/f is too rich it will rise when blipped and then fall below set point and then either die or recover to set point depending on how rich it is.

If you run open vboost the carb farts are even more likely if its too lean.

 

[tugla]

if you have the cover on is the noise from the pipes or still from the carbs to you? i have heard this once or twice but was from the pipes or pipe.......

 

[Rusty McNeil]

True, check this out with the faux cover removed and perhaps the wye as well,

You should be able to tell easily if its a carb backfire or not

 

[redneksoldier]

Check for vacuum leaks around the carb boots, intake flange o--rings and sync nipple plugs. I had the exact same problem. A vacuum leak allows extra air into the intake and well result in a lean condition. Running in a lean condition can also cause pre-ignition ping, and backfire that you will mostly notice at idle and very small throttle openings.

 

[dannymax]

Kyle, that's a carb backfire to me. I think the best thing would be for me to go through the carbs and give them a good cleaning. It's been a few years.

For now, check plugs and look for pre-ignition. You'll see specs if the mixture is pre-igniting. At worst, the electrodes will deform. What gas do you use? I always used 87 non-ethanol. Might be time for some BG 44K to clean out combustion chamber.

I agree with Mark.....start with a good carb cleaning and work outward from there. unk: