Headlight Problem

[jfitz]

I'm trying to get my head and tail lights working on my XR350R. When I bought it, it had no lights. I got the lights from an '84 XR250 parts bike. Since then, I have been trying to figure out whether I have a bad alternator, need a regulator, or?

Thanks to the person who sent me the wiring diagrams, etc. from the manual. Very helpful. Since the update on this site, I can't find the post or name to thank you again. I did get a complete factory manual since.

I get voltage from the alternator, but it's like 27 volts AC and keeps climbing with RPM, so I blew my bulbs. :| The manual shows an "optional" regulator, and there is none to be found on the bike. Makes sense to me that this is the missing link. Another thing is that the alternator test described in the manual says I should get x ohms (can't remember) and it is not within spec. But, how could I get voltage out of it and it not be working? Can anyone help? I can get more details if necessary, I'm just at work and not near the bike right now. Thanks in advance!

 

[Gary B.]

I have a Clymer manual around here, but you'll have to sit tight. I won't have time to look until sometime tonight. Sounds like you need a regulator, though. :think: I'll get back to you!

 

[Gary B.]

My kid's XR doesn't have a regulator, nor is one shown in the book. However, the XL models have them mounted under the fuel tank, above the motor. On my KTM I used a universal regulator (about $15 at local m/c shop) and it's been working for about 8 years now, no problem. e-mail me if you have any other problems or questions.
qcframing@elknet.net

 

[cujet]

Those bikes used a zener diode type regulator. What they do is to use up the excess voltage (generally anything above 13.5V) by conducting it to ground. The fact that is is optional means that if you do not run lights, you do not need the regulator.

Baja Designs and others sell this type of regulator. You can also make one quite easily using Radio Shack parts if you figure out which zener diode(s) you need. Place the diodes (regulator)(along with a heat sink) from the headlight hot wire to the chassis ground.

Do not use any type of standard diode, as this will short 50% of the power to ground!

Chris

 

[jfitz]

Thanks for the replies. Sorry I haven't been able to reply until today. The day after I posted this I went riding at the Badlands with my 10 yr. old son. 15 minutes after we started riding, I caught a root with my left foot, which stopped and killed the bike, broke three bones in my foot and dislocated a toe. :eek: I now understand why people spend the bucks on good boots. I've been home off work and my modem died, so no net access until I returned to work today.

Anyway....while I was off I stopped at the local Honda dealer and found that they were no help except to tell me that the regulator would cost ~$100 and a new alternator coil would be ~$235. :scream:

The wiring diagram in the manual shows an optional different type headlight along with the optional regulator, so I thought maybe the regulator was only required with that headlight?? I may look into getting the alternator from the bike I got the headlight from. Maybe it will fit?? What type XR does your kid have, Gary?

 

[roostafish]

jfitz, do yourself a favor and buy the $15 regulator. You can get them from any dealer and are come from MSR and Moose to name just two. They are extremely simple to wire up and are shunt regulators just like the stock one. Don't bother trying to make one, you'd need one heck of a zener diode to duplicate it and a dropping resistor to boot. I've tried to build these before, and they never are as good as just dropping $15 on a pre packaged unit that is weather sealed.

If you're getting 28vac out of your lighting coil, it's good.

 

[Gary B.]

Yeah, what roostafish said!

 

[jfitz]

Thanks guys, I'll get a regulator. It's great to hear my alternator should be good. That's what was disappointing about the dealer. I asked them what an acceptable voltage range was, and they looked in the same factory manual I had, which frankly, is not as detailed as I'd hoped.