I have an 82 FXRS Shovelhead. I just finished pulling the primary, replacing the trani seals, new sprockets and chain, increased the secondary jet one number, and cleaned out the fuel tank. I went on a first ride today and the bike ran better than ever until after about 80 miles and it got dark then something went strange. The engine started to lunge a little without throttle input. It wasn't missing. At first I thought it was fuel, cracked the filler cap, then filled up but it didn't change the problem. As I went on it got worse then better then a lot worse. I noticed that when it happened the electric tachometer went up about 800 rpm so I think ignition, loose wire? Couldn't fine anything loose. My guess is the automatic advance is momentarily dropping back as there is an instant power loss and the sound of the exhaust changes then it comes back with a feel of a lunge. The module is original stock. Is it just going bad or is there something that could have happened to the wires going to the tack under the tank when I pulled it? The wires from the timing sensor and the plug seem to be OK and the sensor is tight. Timing is spot on, I checked it with a timing light just before the trip.

 

On my stock Ignition ['82 FXRS], the rev limiter quit working [i ran it pretty hard back then] first...I thought it would be OK, but next thing the Ignition took a **** completely.
I was kinda poor then, so ran a Dyna S into it, and it is still in there...

Edit; BTW the Stock Ignition is OK, and if you can locate one from a late Ironhead...It is a Bit better yet in yer Shovel!!!