It has an old battery that isn't holding a charge well - I keep it trickle charging in the garage. Does the bike have aftermarket pipes. If the idle changes, you have a leak. Oh well my credibility on this forum is blown already as a mechanic, anyway so here goes. Give Gumout or Berrymans B12 a shot at it first. Gumout and Berrymans B12 Chemtool are better.
A low idle speed is bad for several reasons. I didn't realize that a low idle speed might be bad. The bike is very low mileage for a '95 and didn't get the frequency of use that it should have for many years I also have a 2001 Goldwing , so the carbs probably need to be cleaned - never been done. I was opening up the idle screw, not using choke, when I was able to suppress the popping on deceleration. At idle the rear cylinder was essentially dead in the water.
Well then leave it like that. I didn't realize that a low idle speed might be bad. It's definitely a popping sound, not a back-firing. Maybe there's a bit more vibration than normal at certain revs but not much really. I've been adjusting the idle revs to be as low as possible without stalling. It doesn't seem to happen at idle revs, only when decelerating from higher revs.
I'll give gumout a try. If you don't have a tach to set the idle speed, your friendly mechanic should do it for you for free. To be fair to the guy, he recommended that I get the carbs cleaned. Give Gumout or Berrymans B12 a shot at it first. It doesn't seem to happen at idle revs, only when decelerating from higher revs. If you made it mostly go away just by upping the idle speed, then all the better. I may not know much about how they work but I do know a bit about making them do what I want.
I will get the carbs cleaned next time it's at the garage but what should I do in the meantime? Maybe I'll try Gumout as well. And replace that bad battery before it leaves you stranded somewhere. I have also read that popping can be due to air entering the pipes through a leak. My guess is they look a little grey or white-ish. When he pulled a spark plug on the rear cyclinder there was no change in rpm, unlike the front cylinder plug.
As I say it helps but I could try something else. Check the vacuum lines also as that is a common problem with popping noises if they are cracked or hard replace them with new ones. . At that point there were more serious issues such as vibration due to insufficient use. The ceased production in 2005. I've been using a fuel cleaner additive and that seems to have helped some.
As I say it helps but I could try something else. I never heard of the one you listed. Also, I was recently told that a poorly charged battery can cause popping on deceleration due to reduced alternator input. I read in Clymer that recommended idle is 750 - 850 rpm. If you made it mostly go away just by upping the idle speed, then all the better. I think you need a new mechanic. .
Retuned, heavier flywheel and redesigned intake give the Vulcan S more low and mid range torque. As for Red Line, it's a synthetic oil additive claimed to do everything 850 is on the low side to start with. It contains no enzymes otherwise I'd use it in the clothes washer. Check the vacuum lines also as that is a common problem with popping noises if they are cracked or hard replace them with new ones. I decided to try the additive and ride the darned thing more to see if it helped - which it did. I have also read that popping can be due to air entering the pipes through a leak.
I like this forum - you guys are a surprisingly patient lot. I've been riding it all this time with no serious issues but the popping has continued. I will check for rust in the tank, check the plugs and get a new battery. The rear cyclinder was running markedly cooler than the front. I shall up it to something much faster but still tolerable.