My bike has started missing sporadically. The other day I was cruising along at a steady 70-75 mph and it just missed...it's done that a few times. It seems to back fire out of the carb and exhaust simultaneously when it misses. Is there any chance this could just be a spark plug. I've checked for loose wires and cannot find any (other than a broken horn wire). With that being said, I cannot get to a whole lot of my wiring without tearing things apart. I can't even get to all of my coil wires without pulling the tank. I can get my fingers to the bottom two screws on the coil and they feel tight but there is no way I can get to the third one. A guy told me that it could be a bad plug acting up sporadically. Does this sound plausible? I changed out the plugs today.

 

My 96 FXDL developed the same symtoms, couple months back. About the 3rd time it backfired & hesitated,( over the course of a couple of days), I glanced down at the speedometer & saw the needle fall & rise back up, in less than a second or two, without ever taking my hand off the throtle. My speedometer reads off a sensor in the transmission. Replaced the ignition switch & solved problem. Don't know of a way to check switch. hth

Ride Safe,
Harold

 

I appreciate the feedback! I'll keep an eye on the speedometer. It wasn't the plugs. I replaced them yesterday and took a couple hundred mile ride today and she was missing quite a bit on the way home. I really noticed it when she was pulling hard. I'm going to check for debris in my tank/carb again but I have yet to ever find any. I'm pretty sure this is something related to the electrical system.

 

I would check/sh!tcan the vacuum operated fuel petcock. I had symptoms like yours a few weeks ago and found the vacuum shut-off valve was stuck half-open. So it would start and run just fun, but miss and splutter and carry on when I gave it a big handfull of throttle under load.

Took the vacuum diaphragm out of the petcock and put on a flat blanking plate, and did away with associated vacuum hose and all came good again.

 

Goto harleys website and register your bike and make sure recalls were done, there was one on the ignition switch. Had mine replaced free. Would stall going down the road then start right back up, confusing to diagnose, there is a testing method in factory service manual

 

As crazy as it sounds check your battery connections. Wire brush them clean of any rust, put some dielectric grease on them and clamp them down good and tight. Be sure to check the other end of the cables too, usually ground to the frame or a tranny bolt, and hot to the solenoid.