Exhaust Pop when I shift

[bweiner10]

Hello all, I have been looking on this board a ton and found out a lot.  Usually I can figure out what I need with out bothering anyone.  I got a new problem that I have not been able to find the answer to.  I get an axhaust pop inbetween shifts, almost a backfire.  Usuallt between 1st and 2nd gear.  Sometimes between 2nd and 3rd.  I also get alot of popping/baffling on decel, but that has been happening for a long time.  Does anyone have any idea of the problem/solution?  Carburetors scare me a bit, but tell me what you guys think. 
Thanks!

[Grumpy]

Vacuum line leaks, usually they crack where they are attached to the carb base. Also exhaust leaks can cause it, check the header bolts for being loose, do not over tighten them, book only calls for 7 ft lbs.

[Ricky-D]

Letting the forum know if you have stock exhaust might make a difference!

And any other modifications also. Motor related that is!

***

[Michvalk]

The intake o-rings leaking can cause this too

[bweiner10]

The only mod is cobra 6 into 6 pipes.  I do not know if it was jetted when they were put on as I bought the bike that way.  This problem was not happening when I got the bik a year or so ago.  Besides that, everything else is for looks. 

[Chrisj CMA]

The only mod is cobra 6 into 6 pipes.  I do not know if it was jetted when they were put on as I bought the bike that way.  This problem was not happening when I got the bik a year or so ago.  Besides that, everything else is for looks.  

+1 on vacuum leaks......check the plugged (unused) nipples real good.  the old OEM plugs dry rot and leak.  Also if the person that installed your Cobras didnt do a good job sealing up them pipes, changing exhaust gaskets or tightening the nuts, you may have an exhaust leak.  Start here just by checking the tightness of the exhaust header nuts (be careful they dont take much torque and break easily)

Also tighten up the 18 screws securing the various tubes connecting the airbox and intake tubes to the carburators.  If you have never done this you will be amazed at how lose they are

[salty1]

Follow up with the above suggestions and the complete a carburetor sychochronization. 

[YoungPUP]

Maybe the 6x6's. I never could tune out the popping on mine.  Partly why they went the way of the Dodo.

[whitestroke]

Maybe the 6x6's. I never could tune out the popping on mine.  Partly why they went the way of the Dodo.

+1



I only had the popping on hard decell.  Don't hear it with the stock pipes, but it's still there.

[Bigwolf]

While you are checking the vacuum lines, don't forget to check the short line on the side of each carb.  These operate the cut valves.  If the cut valve is not working properly, the bike will pop on decel.  Also, be sure to check the PAIR control valve for proper operation.  If the pair control valve does not shut down the PAIR valves when decelerating, that will cause a decel popping.

Bigwolf

[X Ring]

Maybe the 6x6's. I never could tune out the popping on mine.  Partly why they went the way of the Dodo.

Funny, I don't have that problem with your old pipes. 

Marty

[Ricky-D]

I don't know if baffles are available for the 6 into 6 pipes but I know baffles will attenuate the popping noise.

Stock pipes have a built in restriction with the small inner pipe within the headers themselves.

The restriction does not in itself reduce performance per-se and in a lot of cases, improves performance.

If the popping has just been recently occurring and was not present before I would suggest to change where you get your gasoline and additionally put some gasoline additive into the gas tank.

Of course, if you have made some changes to the motor equation, that would be the top suspect for the popping.  Naturally, the header gaskets need to be installed and tightened properly.

***

[saddlesore]

    On the same note, I noticed on the connection between the air filter box and the intakes, the sealer has dried out and mostly fallen off.  Is this something I need to worry about?
   It was mentioned tightening the clamps on the other end could fix the problem so I thought I'd check with the experts.

[whitestroke]

Had to check with Webster 

Definition of ATTENUATE  ???

transitive verb
1
: to make thin or slender
2
: to make thin in consistency : rarefy
3
: to lessen the amount, force, magnitude, or value of : weaken
4
: to reduce the severity, virulence, or vitality of <an attenuated virus>

[salty1]

The decel pop IMO is part of the beast, especially with a 6x6 exhaust system. Even after you have it desmogged, air tight exhaust system, no carb system leaks, tuned to the "hilt", etc., there still will be some decel pop at lower rpm. You can attenuate the pop, but it will never be completely removed. That's been my experience. I can live with it.

[Ricky-D]

    On the same note, I noticed on the connection between the air filter box and the intakes, the sealer has dried out and mostly fallen off.  Is this something I need to worry about?
   It was mentioned tightening the clamps on the other end could fix the problem so I thought I'd check with the experts.

There's been a few threads regarding this. If you want to continue, start a new thread rather that hijacking this one.
Not trying to be mean, just trying to give bweiner 10 respect.

***

[Chrisj CMA]

Maybe the 6x6's. I never could tune out the popping on mine.  Partly why they went the way of the Dodo.

Funny, I don't have that problem with your old pipes. 

Marty

lol....and my cobras have a very slight burbling sometimes at certain rpms at decel, but I like it.....no popping or any negative sounds at all.....I love the sound (with baffles) and will keep them until the law is enforced so I have to put the OEM ones back on

[saddlesore]

    On the same note, I noticed on the connection between the air filter box and the intakes, the sealer has dried out and mostly fallen off.  Is this something I need to worry about?
   It was mentioned tightening the clamps on the other end could fix the problem so I thought I'd check with the experts.

There's been a few threads regarding this. If you want to continue, start a new thread rather that hijacking this one.
Not trying to be mean, just trying to give bweiner 10 respect.

I apologize. no disrespect intended.  I thought that  since vacuum leaks  being brought up as the cause of bweiner 10 's problem, maybe the problem could be solved by my bringing up what I noticed on my bike.
I should have worded it differently.

***

[Mofla]

Clogged # 3 slo jet was the culprit in my case ! I cleaned them all an noticed the three had a good clog in it,, not only did the shift pop go away,, she purrs like a kitty.
Not that hard to clean iffen u got a little patience !!! Cobra pipes here too !!
Good luck !!! Mofla

[shooter64]

I tightened the intake runner screws and it really helped mine. Not sure if that is what you call them. The easy to get to screws that tighten the band around the big rubber tube going from the carbs to the cylinders. Only takes 5 minutes to do. 2 months later, had to do it again a little. I have cobras with no baffles so I guess it will always have a little pop.

[herc770]

I have the popping also.
If some can tell me that nothing is being harmed i can live with it also

[Ricky-D]

I have the popping also.
If some can tell me that nothing is being harmed i can live with it also

Not to worry.

No harm is being done.

***

[97Valk_CT_Euless]

Fought the popping a long time, until I did two things. First, putting extensions on the pilot screws to make them easier to adjust correctly (admittedly, my crappy homemade tool didn't help).  That was the biggest.  Once the screws were actually set to 2 turns (97 Cali model) it made a huge difference.
Second, was getting the cobra 6-6 pipes worked out.  I set the baffles in all the same distance (same as the shortest pipes) and it made a huge difference in the performance and sound.  Went out to 2-1/8 turns on the pilot screws and now she just grumbles on decel.  Best moves I ever made (since running enough cleaner through her to get her in shape).  Runs better than ever too, though still only getting 32-34 mpg.

[Sigrún]

I set the baffles in all the same distance (same as the shortest pipes) and it made a huge difference in the performance and sound. 

97,  would you care to elaborate how exactly did you do this? Do you mean actually reseat the baffles within the pipes by drilling a new hole or something similar?

[97Valk_CT_Euless]

Sure! I wish I'd taken pics but wasn't sure how it'd turn out. I used steel flat stock 3/16 by 1/2 as I recall, drilled both ends, one end tapped to 1/4-20 the other end just drilled 1/4". The baffle screws to the plain end via a nut before insertion (while you can access it) and the tapped end will line up with the original hole to fit the original mounting screw. The bolt attaching the flat stock to the baffle has to be low profile to fit inside the pipe. #1 and #2 are 10" between the holes and #5 and #6 are 6" between the holes. #3 and #4 are original. It isn't exact but it's a lot closer than original Cobra. I'd encourage you to measure the pipe length yourself and see if you agree with my measurements. They aren't the easiest things to measure while on the bike. Note this doesn't do anything for the popping, but it did make the bike run better and more responsive.uch more even sound from the pipes too. I rejected drilling the pipes because you couldn't access the holes to line up the baffles when installing, and years of carbonate it all REAL tight to fit back up. Especially going deeper into the pipes.

[97Valk_CT_Euless]

Sorry. Got confused, I'm not with the bike right now. Got 3-4 and 5-6 confused. 5-6 are the short pipes and are original.

[Sigrún]

Wow, thanks 97

I'll have a little looksee into the cobras with some thought with your instructions in mind. To be totally honest, I never even thought about the whole thing earlier, but yes, it does make perfect sense. Also, the popping is least of my worries but if there is a noticeable difference in performance ( and perhaps even mpg ) I'll certainly consider this very seriously

[Ricky-D]

That's a real good idea regarding placing the baffles correspondingly to each pipe.

Kind of like tuning the exhaust.

Which should always, if done properly, make an improvement in performance and economy.

***

[97Valk_CT_Euless]

Well it certainly wasn't scientific (no dyno) and I don't mean to make it sound like a supercharger, but from a seat of the pants standpoint the bike feels and sounds better to me. Cheap too, if a bit time consuming. But hey, what better way to consume time! Bweiner10, did you get your popping fixed?