My SG has just over 65K miles on it. Stage I, no engine mods. I take good care of it and do my own maintenance. The last thing I did to the engine was when I put in new HD cam tensioners and all four cam bearings around 3000 miles ago. Everything went textbook and my Glide has been running strong since.

About a month or so ago, during the first hard freeze cold spell we had down here, I noticed a very slight but noticeable drop-off in performance on the high end. Nothing alarming, but I did notice. Over the next few weeks, I noticed that the rare but occasional decel backfire it would do when it was cold starting increasing to almost daily. The plugs looked a little lean so I tweaked the mixture out 1/8 turn and everything seemed to get better but it was still off.

Then a couple of weeks ago, I did a speed run across town and noticed that it was decel backfiring constantly and just not right on the throttle. The backfiring would get better if I pulled the enricher so I was thinking I had a carb/vacuum leak problem.

Long story short, I have been through the carb twice, did a extensive cleaning, inspection, and rebuild the second time, replaced the intake gaskets, replaced the MAP sensor, replaced the exhaust gaskets, put in a SE performance ignition module and coil, put on new SE fat wires and HD std plugs. The problem got worse. Now, it will still crank right up and idle with the enricher out but it is rough and responds to the throttle with blow-back, falling flat, backfiring, and everything else but accelerating smoothly...and dies when the enricher is pushed in.

I'm running out of options here...get a new CPS and if that isn't the problem, WTF?

 

Is there a fuel Filter located anywhere on that bike?
Is there a Fuel Screen between the Tank and the Carb you may have forgotten to clean?

 

The vacuum operated petcock maybe checking out and not providing the flow it once did, another would be the filter on the petcock. A wild shot here, try running the bike with the fuel cap real loose, maybe a plugged vent hole in the cap.

 

My first thought was air leak at the intakes, then maybe exhaust leak....

I would double check for leaks, then I would drain your tank, check all fuel filters, refill with good gas (could be bad gas) ...could be petcock ...they have been known to fail

Last would be ignition module

Try to think back to just before it started...was anything changed or done to it?

 

I replaced the vacuum petcock with an aircraft fuel valve awhile back and put a new filter on when I painted the tank this past summer. I pulled the valve and checked and cleaned the screen when I changed the cams and there was nothing going on there but it is certainly worth checking again. I usually get premium gas at name brand stations but that is also something that is easy to check.

The last thing I did to the bike was to replace the front brake master cylinder with a used chrome one and before that I installed a HID headlight system. I thought about an electrical issue but the charging system output checks normal and I could not find any loose connections anywhere. As I checked, I cleaned and dielectric greased the connectors.

 

 

I thought about that earlier in my quest and I did find a small exhaust leak at the rear gasket 11:00 position because the upper nut had worked loose...because I forgot to retorque them after replacing the tensioners. I pulled the pipes and looked them over real good and replaced both gaskets with new OEM cone gaskets. I do not see a leak now.

 

 

Could be bad fuel or water in the fuel tank. Remember, water is heavier than fuel and will be the first thing to leave the gas tank and enter the fuel injection/carb.
You did not mention if you are on the same tank of fuel that you were on when this running problem started. "If" you are on the same tank of fuel... I would pull the fuel line off the fuel injection end of the fuel line, drain the whole tank of fuel out, use a Gas Can and go get a gallon of fresh fuel, from a Different gas station.

 

If it's running rough, you might want to do a compression test, and cylinder leakdown test. A burned exhaust valve could be the cause. If the valve clearance wasn't correct on reassembly after your cam bearing replacement, it can cause the valve to burn. This is also supported by your spark plugs having evidence of a lean burn.