View Full Version : Electrical problems - 1975 Honda XL250, DFW area
06-08-2005, 01:27 AM
I thought I would try asking for help as I am stumped. I'm in Grand Prairie and I own a '75 Honda XL250.
It was not running when I bought it this past January, but everything was there. I wanted to get it in running condition to put back on the street. I've spent the last 5 months getting it running and it runs fine; starts first kick.
However, there is a problem with the electrical circuit that has me so stumped I cannot figure it out. Basically, everything works (horn, tail-, brake- and head-lights) but when I apply the brakes, the lights dim and eventually runs the battery down.
I have the Clymer manual and the Owners Manual wiring diagram. I've checked everything I know to check and they all seem OK. I just cannot figure out what is causing the voltage/amperage drain. And the wiring diagrams confuse the heck out of me.
IF, there is anyone on the board in the DFW area who is knowledgeable in motorcycle electronics, and can help me out, please let me know? I don't know what I can offer in return, but I will try.
You can contact me at:
06-08-2005, 08:24 AM
Sounds to me like a generator/alternator or regulator/rectifier problem.
06-08-2005, 05:52 PM
Have you checked the voltage at the battery with the bike running? At idle with the lights on it should be at or above 12.5 volts, but not over 15 volts. 13-14 volts would be ideal. Next, rev up the engine to around 4,000 rpm and check the voltage at the battery again. It should be between 13.5 and 15 volts. The figures I'm giving are generic. You should check your Clymer manual to ensure that these voltages are correct for your bike.
If any of the readings are outside of the above mentioned figures, you probably have a bad charging system. Here is a link that has a really good troubleshooting chart for the charging system:
It will help you determine if the regulator/rectifier, the stator, or both may be bad.
Electrosport also sells aftermarket charging system components that are of good quality and price.
Another possibility is that one of the cells in the battery is weak. You can check for this by purchasing an inexpensive (> $5) ball type tester at most auto parts stores. It is a small syringe looking thing that you suck some of the battery acid into and then read the number of balls floating. It will show the specific gravity for each cell of the battery and let you know if one of them has gone south. Be sure to fully charge the battery before checking it.
Alternately, you can load test the battery, but a load test is not quite as accurate as checking the specific gravity.
Good luck and keep us posted!
06-08-2005, 06:58 PM
I have the Clymer manual and the Owners Manual wiring diagram. I've checked everything I know to check and they all seem OK.
I assume this means you checked the battery ground? Also, if you rev it, does the headlight get dimmer, or brighter?
06-08-2005, 08:36 PM
Thanks for the replies.
The bike is a 6V system with a new battery. I checked the Rectifier per the Clymer manual and it checks OK. I checked the Generator per Clymer and it checks OK. The headlight is a different circuit with AC voltage; the other lights are DC.
I will check the battery voltage while the engine is running; I will compare it to the Clymer manual voltages. And, I will do what the website posted suggested of disconnecting EACH wire connection and cleaning with cleaner. I will try the suggested flow chart and see where I end up.
I'd really like to get this vintage bike back on the road. It really is a nice riding bike and I think I could really enjoy it riding around town.
06-08-2005, 09:42 PM
06-09-2005, 03:33 AM
Here is my 1975 Honda XL250:
Here is my webpage for my other bikes: '03 Honda CRF230F & '75 Honda TL125 trials bike:
06-09-2005, 07:58 AM
I looked at a clean XL350 really seriously once, could have picked it up for $600 (about 8 years ago). I still don't know why I didn't buy it. I'd also love to have a vintage trials bike, talk about hard to find!
06-09-2005, 12:52 PM
OOooohhh!!! I like the bike! :-D
03-25-2009, 05:08 PM
Larry, I sent you a long winded post on things to check on your XL. I just went through this myself on one of my XL's. The system on this bike is weak and very sensitive to any little thing not being just right.
03-27-2009, 03:20 PM
That looks sweet. Nice. Good luck on the electrical gremlins.
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