Bonneville America Forums Forums Technical Forums Exhaust Popping - what's normal?

I get little popping sounds when idling. No great explosions, just a noticable "putt putt." Is there an amount of normal popping that I should expect, or do I need to do something that involves tools?

I have seen some related posts in the archives, but when someone talks about "1 and half turns of the idler screw," I shamedly have to admit to not knowing what one of these is and where to find it. Hell, I'm just impressed that I know the word popping !

OK, so I am a complete engineering ignoramus - but I'm willing to learn

Siggy

If you look over the pages here, http://members.bluefrog.com/~pwhitbec/Triumph/carbs0.html you will come out an expert on carb tuning. They are complete with lots of pictures, so don't feel intimidated.

At idle, there shouldn't be any popping unless the carburettors are seriously out of adjustment, the sparkplugs are getting tired, there is some water or other stuff in the gas, or you are badly in need of a valve adjustment.
Another thing that might be causing an occasional pop at idle is if the idle speed is a little low. Because of the way the electronic ignition on these bikes works, a slow idle can make the signal telling the ignition when to spark a little fuzzy.

As for what is normal, some snapping and popping while decelerating will be experienced with modified pipes. It might be there with the stock ones as well, but you can't hear it.

Greybeard,

Thanks for the link. I - gulp - now know where the "idle set screw" is! I didn't even know that I could (a) find it and (b) do something with it. First thing tomorrow I will see if adjusting this makes any difference - and I guess this is the simplest thing to try first before I rush out and buy tools.

If it works, I'll buy you a virtual beer - tell me your favorite drink and I'll post the web address

Siggy

Got a problem with popping myself since i put the new thunderbike pipes on, does the air mix screws have something to do with this? the instructions said to back them off one full turn which I have done.

If all else is OK, adjusting the idle mixture a bit rich will help. Make sure you don't have an exhaust leak where the silencers slip onto the headpipes. Also, remove the air injection system if you haven't yet. One thing I found on mine was that the mixture required to stop the Epco pipes from popping was so rich that my top speed was suffering.