Let me start off with that this will be long winded so that I can tell you everything that I have done and experienced with my current problem. I hope that people read this even though it's very very long. Hopefully we here can figure this thing out. I WANT TO RIDE LOL.

I have a 1985 FXEF all stock with the 1340 evo engine, 4 speed trans with the kick start. My problem is that this bike with run great without any problems. Then, sporadically, I start having a run-ability problem where it starts backfiring from the exhaust and the carb. Popping, spitting back etc. Now sometimes it goes away while I'm riding sometimes it doesn't. It also seems like after I crank the throttle hard a few times it quits acting up, sometimes it doesn't help. I have messed with all of the wires and fixed a couple of connectors. I replaced the ign system because it was acting like a back pickup. I have the elec ign, not points. I put in a Dynatek 2000i Ignition D2KI-1P. I went and timed it. Soon as I started it after the change and timing, it was acting up right away, this didn't fix it.

Next, I went through all of the wiring checking grounds, power, circuits, CBs, relays and connectors. Now I moved to the charging and coil. Both while running and not running. Turn on the ign switch and I have 12.2v everywhere. Nothing seems wrong while the engine is off. Power to the coil which I'm running in dual fire mode (both plugs fire at the same time). Now while the engine is running, this is where I have found issues. On my coil, one of the small terminals holds at charging voltage (14ish) now when I rev the engine I see issues, one of the small lugs goes to 13.2ish and the other lug drops down to about 7 volts and when I go back to idle, it comes back to 14.2. I have checked the the A/C volts from the stator and as I rev up to the 2k mark, I'm showing almost 75 volts A/C and at idle I think it was about 30ish. I think I may have a bad stator from everything I've read. I have changed out the coil with another one that was good and the problem was still there, no change.

Bottom line, the bit*h keeps popping/backfiring from the carb and exhaust. It is so bad that while riding, I cannot accelerate to shift gears. It just gets worse and worse. I pull over and blast the throttle a few times, and sometimes it stops acting up and I can ride like nothing was ever wrong. But most of the time, if it starts when I leave my house, I have to turn around and come back home to park it. But then the next day, I can come out and start it without any issues. It does it cold, hot, just not rhyme or reason to the stumbling. I have an inline clear fuel filter and can watch the fuel flow. I took the fuel line off and put it in a can and the fuel just flowed right out. So no fuel issue. I have removed the carb, a S&S super E, pulled it apart and checked all of the internals. Everything seems clean and operational. But maybe the accelerator pump is jacked up, but I can't find anything with it. This problem does almost seem like it's just getting choked or leaned out when I open the throttle. But the electrical voltage drop really has me confused, is that part working right? The drop in voltage at the coil when I open the throttle doesn't seem like it should do that. I'm really at a loss. It has to be either the loss in voltage at the coil (and I think I lose voltage at the battery as well) which means that I need to replace the entire charging system, or it's a fuel delivery issue at the carb. I have it timed correctly. If I try to adjust the timing from where it's currently at, it really acts up.

Thank you for reading this whole thing. Please, if I have confused anyone, let me know where I need to clarify and I'll try. Please, I hope that someone here has some input. TIA

 

Tom, take a deep breath! For starters we have an Evo Section, where you can meet fellow owners, who can help solve your problems, so for pete's sake call over there.

My guess is that your ignition system pickup is failing, as mine did some years ago. It's inside the timing cone.