QuestionI have a 1987 VN1500 that has me stumped. It misfires on both cylinders, mostly on acceleration. I used spark testers on both cylinders and I could see that both were misfiring at the same time. Pickup coils (it has 2)were tested and are within range. If the battery is the least bit low it does not fire on cranking and will not start. It has a new stator and is charging well. I have checked wire connections and can't seem to find a problem. Any help would be appreciated.
Thanks
AnswerStarr, I don't know anything about the Vulcans, but from the sound of it, I would have the battery fully-charged and load-tested. A viable battery should be able to crank the motor over numerous times (15 seconds at a try, then wait 30 seconds) and power up the ignition system.
If the battery is good, but the system isn't charging, then the regulator-rectifier may be at fault. Electronic systems have a threshold where they quit working, usually down around 10 volts, so if your battery is dipping below that range during cranking and isn't recovering back to 12-13 volts, then you will have a misfire and hard starting.
I would install the best quality battery you can find for it and see if the problems don't go away completely.
If the battery doesn't mend it, then the ignition control module would be the last stop, assuming that you have good coils and spark plug caps. Fresh spark plugs would be recommended too, if they are older.
Bill Silver
