I own a '99 Superglide Sport (FXDX). It has 16,000 miles on it, no aftermarket engine work doneor extra lights, etc. The other day-without notice it started backfiring, then the gauges started doing a bunch of random stuff. Eventually (approx. 2 mins. of backfiring) it shut off, and would not start. I was out riding in the middle of nowhere, so I had one of my riding buddies push start me, and it started; however it only ran for a few more minutes then died. Another buddy of mine had just enough tools in his toolbag to swap out batteries with me and sure enough that did the trick (his battery worked in my bike, and mine didn't work in his).

After getting a brand new battery, the bike ran great for an hour or so, then started the same thing again. I checked all of the connections, grounds, battery terminals, etc. and all appear to be connected, tight, and free of debris.

If I put a charge on the battery it will only run for a short bit (30-50 minutes) then start backfiring, eventually shutting off.

Sorry for the longer post-I just wanted to put enough details to pinpoint the problem. I have also tried searching the forum for answers; however, I cannot find an issue similar to mine.

Thanks ahead of time for all of the help. I will also post whatever the solution that works turns out to be!

 

you need to replace whatever supplies juice to the battery....voltage regulator?

 

yup, time to troubleshoot the charging system. its not topping off the battery, check the regulator first. On some old bikes, if the bike runs without the battery hooked up, the charging system works, if not then somethings wrong. Not sure about some of the newer bikes though. Folks on this forum will have answers though, I'm sure.

 

I appreciate the help thus far guys. Is there any tests that I can conduct inorder to confirm or deny that it is the voltage regulator w/o replacing it first?

Any other feedback would be grealty appreciated!

Thanks again.

 

I am a little baffled by the backfiring, but it sounds like you may have a charging problem because it sounds like it is not being recharged.
The drawback to that guess, is that a good borrowed battery should not be run flat in as little as 30 to 50 minutes of riding. So there may be a problem other than the charging system, but that is the best place to begin.

I assume your bike has an alternator enclosed in the primary case? If so, disconnect the stator to voltage regulator wires at the plug up front, after the key is OFF.
To check the stator:
Attach one lead from an ohmmeter to either of the stator sockets. Attach the other lead to a good ground.
A good stator will show no continuity across either stator socket. Any other reading indicates a grounded stator which must be replaced.

Next, remove the ground lead and put it into the other socket of the stator socket. Set the ohmmeter to the RX1 scale. Resistance across the stator will be 0.1-0.2 ohms. If the resistance is lower than that the stator is shorted and must be replaced. If resistance is higher, the stator has an open and must be replaced.

Check the AC output:
Connect an AC volt meter across the socket.
Run the engine at 2000 rpms. The AC voltage should read 32 to 40AC, approximately 16 to 20 volts AC per every 1000 rpms. If the output is low, this can be a faulty stator or a faulty rotor.
If the output is good, I would then move on to checking the voltage regulator/rectifier next.......pg

 

Use an OHM meter to test voltage output when the bikes running and then again when not running. If they're similiar to cars you should see about 11.7 volts not running and about 13.7 volts when running.
If there is no difference between the 2 readings, you have a prob with the charging system. Could be something as simple as a bad battery cable or ???????

 

Start the bike then remove the positive battery lead. If it dies, you're running off the battery and not the alternator.

 

Huh-nnn? That makes no sense.
If you start the bike and remove the positive lead, of course the bike is going to die.
It has no electrical power at all at that point! The alternator and battery both have just been disconnected.
I must have missed something here. Pardon me if I did.....pg

 

That is a smokin' Ironhead, Piniongear.

 

Baggersteve...
Thanks for the flowers. I have owned this old bike since 1973........pg