Motorcycle Repair: backfiring on deceleration, pop pop pop, kawasaki vulcan

Question
" I have a 98 Kawasaki Vulcan Classic 1500E1 with Thunder Intake and Cobra Pipes. I did some minor maintenance on my bike a couple of months ago. New Spark Plugs ( I didn't know at the time but they were one step higher temp than spec), Oil Change, Coolant change. I did this because I just bought the bike about 4 months ago and I wanted to make sure everything is okay. I should say that all the fluids and plugs looked pretty good that I replaced. I originally used mid grade gas because that is what the previous owner told to use but for the last month or so on the advise of a "seasoned cruiser rider" I started using 93 octane gas. It seemed a while back ago that the bike seemed to be running hotter. I mean I could feel the heat from my exhaust pipe against the back of my leg after riding a while and I didn't remember feeling it previously. The bike does not seem to be missing or anything like that and it seems to run well idles well. It is getting poorer gas mileage. About three days ago it started backfiring on deceleration pop pop pop with an occasionally kapow. It gets worse as the bike gets hotter. I changed out the plugs to the specified heat range thinking maybe it was a culprit. The month old plugs I took out were black and sooty around the edges. The new plugs made no difference. I took off the air cleaner that I cleaned a couple of months ago to see if that had an effect and the was no change. like i said the bike seems to run great except for worse gas milage. it feels a little hotter (not overheating hot but just hotter)and backfiring (mostly popping) on deceleration Any suggestions on what to look for or do.  

Answer
Hi Wade.
 Start by going over the whole engine for a tune-up.  Check the valves and timing, carb synch and air filter.  Check for hot grounds on the ignition circuit as well as places where the ignition wiring could be grounding against the frame or engine.

As far as the popping is concerned, if you are slowing down by using the engine to do it, then the popping would be normal if the valve gap and timing were off.

Start with all of that and see what you find.
Good luck.
FALCON