Popping on decel

[biguglyman]

Have read a lot of good info here on this problem. I plan on doing a redeye desmog and replace exhaust gaskets. I'm pretty sure I read somewhere here about little anti-backfire things attached to the carbs but can't seem to find what they're called or where to get them. I figure as long as I'm in there doing the desmog, I might as well replace them buggers and the vacuum lines that attach them. Maybe I'll get all the parts together and bring them to Inzane and one of you kind, helpful Valk-veterans can help guide me through the process if I don't get it done before then.

[Red Diamond]

From what I have seen under the carbs, should you desmog, you will eliminate all the vacuum lines with the exception of the #6 to the petcock.

[biguglyman]

I was under the impression that there was some kind of little anti-backfire valve attached to each carb.

[fudgie]

I think there are tiny vent? lines on the back of each carb, if thats what you mean.

[salty1]

Are you thinking of air cut-off valves? My 97 is desmogged and tuned to the hilt, but still will pop some on decel at operating temps and lower rpm's. I'm of the opinion it's inherent in the beast with Cobra 6 into 6 pipes. A member with handle Whitestroke has wrestled with this issue too. Keep us posted.

[Bigwolf]

I'm pretty sure I read somewhere here about little anti-backfire things attached to the carbs but can't seem to find what they're called or where to get them. I figure as long as I'm in there doing the desmog, I might as well replace them buggers and the vacuum lines that attach them.

Those "little anti-backfire things" are called air cut valves.  I would suggest testing them since 5 were leaking on my standard at 25k.  Deffinitely replace the rubber tubing that connects their vacuum side to the carb.  They are quite pricey for such small pieces.......I am thinking it was $75 each last spring.  That comes to $450 for the set!  Don't know what they cost now.  You can get them from HDL or from SUDCO.

Bigwolf

[biguglyman]

Well THAT'S a job that's going to wait until I'm sure it needs it. Valves are @60 bucks a piece! I'll check the hoses while I'm in there and see what happens. I actually like a little of the popping but it's gotten gradually worse. I DO like the 6x6 cobras.

[Chiefy]

I'm not a gifted wrench, so take this with a grain of salt.  Popping and backfiring can be caused by a lot of things.  On a carburatored engine, a lean mix can do it.  Get a little tool and set your mix while you're in there.  Redeye sells one.  With my fat fingers their tool was a little difficult for me to use, don't know if an easier to use one is out there.  You also want to replace the Orings under your air intakes.  Cheap and easy, and leaks cause popping.  The desmog will eliminate many potential air leaks.  The Redeye kit comes with good instructions.  And the guy who sells them answers email the same day, although perhaps not in minutes.  Read the instructions a few times, and go in front of the bike and do a dry run.  If something seems iffy, ask Redeye before you start. 

[salty1]

I'm not a gifted wrench, so take this with a grain of salt.  Popping and backfiring can be caused by a lot of things.  On a carburatored engine, a lean mix can do it.  Get a little tool and set your mix while you're in there.  Redeye sells one.  With my fat fingers their tool was a little difficult for me to use, don't know if an easier to use one is out there.  You also want to replace the Orings under your air intakes.  Cheap and easy, and leaks cause popping.  The desmog will eliminate many potential air leaks.  The Redeye kit comes with good instructions.  And the guy who sells them answers email the same day, although perhaps not in minutes.  Read the instructions a few times, and go in front of the bike and do a dry run.  If something seems iffy, ask Redeye before you start. 

As follow up to Chiefy's comments, your pilot jets could be set at 2 1/4 turns out.

[Patrick]

If you're going to de-smog then you might as well change the cut-off valve hoses. Its about time for hose replacement on all these monsters if they haven't been changed. Some of those valves could very well be leaking, but, they're expensive little thingys. The popping is usually vacuum hoses and/or exhaust gaskets. It s also a good idea to set the pilots at 2.25 turns if they haven't already [and if you still have 35 low jets].

[MarcusS]

My bike was making lots of noise on coast and de accell. It had open super trap aftermarket pipes when I got it and the pipes looked cooked. It ran and sounded great at high speed but did not run smoth under 2000 rpm. My mechanic said that the unit was running lean and needed rejetted due to the open pipes. After jetting and replacing the disk on the back of the mufflers I have been able to smoothe it out. I do thing my idle jets were dirty because after several months of using about 2-3 oz of sea foam I think I have it cleared.  The pilot jet setting on mine is around 2.75 using the RPM drop method.  Carb kit instructed intial setting at 2.5 and it ran OK.
I tune pilots and sync about every other month sense  I got the bike last August. I know I am running rich at idel but it is so smooth at 1200 rpm under a load I don't care.

Before you start turning wrenches try some carb cleaner in the fuel to open up any jets that are clogged. Another cheap trick is to spray carb cleaner around to find vacume leaks and bad exhaust gaskets.  Medication is a much beter option to surgary.