1974 Honda XL 70 - Charging system advice?

#1
Hey guys, first time poster, long time reader. Great forum by the way. I'll try to make this short and sweet and any help is greatly appreciated. :)

A few months ago, my friend decided to go ahead and splurge on a 1974 (I think that's the year, anyway) XL 70 and basically his electrical system was really hacked up by the previous owner. The guy was even nice enough to give him a print out of a wiring diagram for a completley different model from Honda.

Anyway, it turns out that the iginition switch which had been sold with the bike was not original (judging by the wiring diagram's call for a seven or eight terminal switch; as opposed to the bike's aftermarket four). So to compensate, the previous owner hacked up the majority of the wires coming from the harness and basically piled them all together on one circuit. It's a long story but if anyone needs to know more feel free and ask away.

After explaining this to my friend, I ended up recommending he get an original honda switch as well as a spare wiring harness. I ended up swiping the female end of the ignition switch socket connector from the harness he bought since the previous owner wired in a square connector to fit with the aftermarket ignition that's actually on the bike... Hope that made sense.

After a couple weeks of tinkering, I managed to hook everything up according to Honda specs.

Here's the problem. After going over the diagram a bunch of times, I've realized that the battery only gets charge if the engine's running with the headlight on (correct me if I'm wrong). To me, this seems a little awkward since if you do mostly day riding your battery is eventually going to die.

I've also realized that the tail light needs power for night riding, too. So ultimately, after the power get sapped by these two there's little left over to actually charge the battery.

My question is... Would you guys ultimately recommend I wire up a separate, dedicated circuit coming from the alternator to the rectifier so that he'd get charge whether his headlight were on or off? I know power follows the path of least resistance, so for night riding I was thinking of maybe putting in a switch on that circuit so that the current coming from the alternator going directly to the rectifier could be broken, in order for current to go through the headlight. Does this make sense? What do you guys think? Any suggestions are much appreciated.

Thanks for the help!

-mdc :punk:
 

Neck

Growing up is optional
#2
Basically the charging system didn't have a voltage regulator so without the headlight on the battery would over charge, and the engine doesn't need the battery to run, the ignition coil is magneto powered, separate from the charging system. You could use the brakes many times and not kill the battery, and even if you did kill it, you could still start the engine.
 
#3
Your system might have two circuits a seperate ignition system that supplies voltage to the ignition coil, points, condenser etc.
The other circuit should would be your charging system for your lights horn and to charge the battery.

I'm not sure if you ran the bike and checked for more than battery voltage with the headlight on and then off. ?? or your reading the diagram only.

I know reading wiring diagrams can be confusing and sometimes incorrect.

It wont hurt to run a separate charging curcuit directly from your voltage regulator to your battery.
Hope this helps
Cheers Paul
 
#4
Hey guys thanks for the help.

I've tested the charge circuit coming from the alternator which is hooked up to charge the battery and it looks like its working, but only when the headlight's on. I noticed that the bike gets it's charge a lot faster if I disconnect the tail light, but this isn't practical for night riding.

I plan on putting in a separate wire coming from the alternator wire going to the rectifier (separated by a switch) and see if my buddy can have his battery charged during the day. The only problem is that I'm a little paranoid about breaking something, since the way honda has these bikes charged is a little weird to me.

Anyone think I'm going to be making things worse before they get better?

Thanks. :smile:
 
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