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Electrical problem on a reclaimation project

Posted: Mon Nov 18, 2019 5:17 am
by Popejoeii
So, a couple weeks ago I bought a crashed RH50 from the city impound auction. Front forks mangled all to hell, few bits of destroyed plastic, figured it wouldn't be a bad investment for $250.
A set of $325 forks, some plastic bits new and used, new locks with keys, and some other little things, and all of a sudden I'm in for almost a grand so I hope this thing is as much fun as I've read. Lol.
I get almost everything back together, but before I do I start her up to make sure everything is good, and I discover a super weird electrical problem. Before anyone asks, not only did I search the forums but I also browsed through all 19 pages of the RH forum looking at posts for a problem like mine. I really did try.
First, the scooter will start just fine with the push button, but not at all with the kick-start.
Then, when running, none of the lights on the instrument panel work, nor the fuel gauge, blinkers or hazards, tail light or headlight. But the horn does, and so does the kill switch and speedo.
I looked around for a loose ground, but all I could find was the one by the voltage regulator and it was quite snug. I wouldn't expect it to be a battery problem because the electric starter turns over strong, but maybe the regulator or generator perhaps? Not sure where to go from here, all thoughts are appreciated.

Posted: Fri Nov 22, 2019 3:36 pm
by Stanza
If it's not getting power through the AC or DC lines, it's possible that you have a regulator problem. It's odd for one of these to be flat dead electrically, even with a dying regulator, but perhaps someone installed the wrong one on your bike?

The other possibility is that the regulator had previously failed, and all the bulbs you mentioned are burnt out. Can you confirm?

You can test to see if power is getting to the regulator by using a voltage meter (set it to AC current) and measure the voltage on the white wire (positive lead on the multimeter on the wire you're testing, black lead on a good grounding point), and yellow wire one by one. Then, measure DC voltage at the red/white wire. Post results here, and we can go from there.

Thank you, Stanza

Posted: Fri Nov 22, 2019 4:40 pm
by Popejoeii
Genuinely sorry about the cross-post, but it was the "getting 30 views in 3 1/2 days" thing that motivated it.
I can confirm that none of the bulbs are burned out. Neither instrument cluster nor blinkers/headlights.
I will check regulator voltages and post results this evening after work, and I appreciate you responding.

Posted: Mon Nov 25, 2019 12:53 am
by Popejoeii
So, all the voltages seem to be pretty normal. 12.2dc on the red and white wire, and 14.2-14.5 AC on both the white and yellow wires while running.

Posted: Mon Nov 25, 2019 3:35 pm
by Stanza
The white wire is on the low side, that should be up near 16v at idle. The red/white wire should be high 12s, but that's all charging circuit related. So if your yellow wire is getting the proper voltage (which it is), then your next step is to see what's going on with the lighting circuit. Take your headlight off and measure ac voltage at the wires going to the socket. You should have three wires. Blue, Brown/white, and Black. Black will be your ground connection, blue and brown/white are for high or low beam (can't remember which is which though).

Test both, and then try hooking your ground to the frame instead, to rule out a bad grounding via the harness. If you aren't getting any voltage, no way no how, then backtrack to the high/low beam switch and check AC voltage at the yellow wire there. If you have voltage going to the switch via the yellow line, but nothing coming out via blue or brown/white, then your switch is toast.

If you have no voltage at the yellow line going to the switch, but you DO have voltage back at the regulator, then it means you have a short in the harness somewhere and you need to put on some relaxing music while you go hunting for the short.

Posted: Fri Nov 29, 2019 2:05 am
by Popejoeii
Should I have that voltage with the key in the on position, or only while the scooter is running?

Posted: Mon Dec 02, 2019 2:51 pm
by Stanza
With the engine running. Your AC (lighting) circuit is only powered while the engine is running. The DC circuit (starter, horn, turn signals, brake light) is connected to the battery, so it will have power even if the engine is not running (though the key does need to be in the on position).