I have a 2010 Iron 883 w/ V&H short shots and about 5k miles. I got it in May from a private seller.

It was originally getting about 25-30 mpg, before I changed my spark plugs. They looked black. Once the new ones were in, MPG jumped up to 30-35 mpg which still seems low.

Bike was running fine overall until this happened:

Was out riding back roads for a couple of hours. Ended up on the freeway, and got off at an exit. At the red light at the end of the exit ramp, I noticed my bike was idling weird like it was about to stall. Light turned green, and got to another red light. Same thing happened, only this time the bike died and wouldn't start back up. I tried getting it started by giving it some gas, and it finally fired up, but wouldn't stay on unless I was revving it up.

Got it towed home, looked up some stuff online, talked to some people.... Tried starting it again, but this time it was just clicking. Changed the spark plugs (which were black after about 2,000 miles of riding) and it still wouldn't start. Checked the battery and it was only reading 11.6 volts. It was the original battery manufactured in 2009. I replaced it, and the bike fired right up. Seemed to be running decent after that.

Then, my 2nd or 3rd short ride since replacing the battery, I was riding for about 20 or 30 miles, and all of a sudden I noticed my bike starting to crap out like it was about to stall. This happened when I slowed down and squeezed the clutch to downshift before approaching a downhill curve. I pulled over and the bike sounded like it was about to stall out. I turned around and made it to a gas station, but got to a point where the bike wouldn't stay on unless I was giving it gas. I refueled, and got the bike started again, but had to ride back home while giving it throttle the entire time. If I let the bike idle it would start to stall out.

When I got home, I parked and let it idle to see what would happen. It was barely running, but I gave it a blip of gas and it seemed to balance back out and stay running for about 5 minutes before I shut it off. I have ridden several times since then, but just short jaunts across town with no noticeable issues.

Last weekend I was out for ride and had been going for about 45 minutes or so, and got off an exit after going about 55mph, and when I was slowing down at the red light, same thing.... Started crapping out again. Had to ride home giving it throttle the whole time or else it would stall. Got home, let it idle and it was about to stall so I gave it a blip of gas and it leveled out again....

At this point my gas mileage has been down to about 20-25 mpg...

Not exactly how I had hoped to end the riding season.

Any ideas?

 

Your 2010 has an EFI so detecting if a engine is running rich or lean by looking at the spark plugs is not an easy task. On a engine with a carb, black on the plugs might indicate a fuel mixture that is too rich. However a weak spark could cause that symptom as well. You don't have to keep replacing the spark plugs, especially if they're new, just use some carb cleaner.

A weak spark could be a symptom of a weak battery and/or charging system, but I would not start there. The battery itself cannot sustain a running engine, you also need the charging system. If the engine is not getting enough fuel to maintain enough RPM's so the charging system can work efficiently, it might give you symptoms of a dead battery.

Since you mentioned you have V&H short shots I'm assuming there is some sort of aftermarket tuner, like the V&H Fuelpak, under the seat. Regardless if it's a bypass tuner like the Fuelpak or a flash tuner like the Power Commander, they all have a setting that regulates how much fuel the EFI gets when decelerating. I would first check and re-enter the tuner map if you have a tuner before you continue spending cash on parts you might not need.

Good Luck!