Members who have donated towards server costs
Join Date: Nov 2007
Location: Chandler, Arizona
If you are completely off the throttle, and have the clutch pulled in, basically you are at idle. With the clutch in, it makes no difference whether you are moving or not. Does it do this when sitting still, idling in gear with the clutch in?
"Coasting" is what I call "trailing throttle" which means closed throttle while in gear and clutch out, to utilize engine braking. Under that condition many bikes will pop and backfire slightly, even when everything is set right. That is something I do all the time when slowing down and speeding up. I will have the throttle open while climbing a hill, then close it or partially close it when starting back down. I also do it when coming to a stop sign or light. I usually don't start downshifting until I have reached a fairly low speed, unless I need to lower my cruising speed, and need to go down one gear to prevent lugging the engine.
But none of that sounds like your problem. I also don't think it is an air link. It sounds like something is wrong either in the throttle linkage, the throttle itself, the cables, or it could also be an issue with the slides or diaphragms. I personally hate CV carbs, They were originally designed as an emissions control device, they do allow the carb to operate over a wider altitude range without rejetting, but they can also be a RPITA when things aren't right.
I would check your cables first, to see if they might be binding. The Vulcan has a dual cable setup, something else I never liked. It causes twice as much cable friction. I removed my decel cable (not only on the Vulcan, but on 2 other bikes as well) and am just using one cable, to open the throttle, and the spring on the carbs closes it. The throttle snaps closed much faster and easier with just one cable.
I am a motorcyclist, NOT a biker.
1997 Vulcan 750, purchased about a week ago
2006 Sportster 1200 Low
2013 Royal Enfield Bullet 500, converted to carb
2001 Yamaha XT225, heavily modified
2004 Honda Rebel 250
1979 Vespa P200E
2002 Vulcan 750 parts bike
1994 Yamaha XT225 parts bike