What's normal voltage drop for key on?

Supercoyote

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Recently replaced my regulator with the common R292, wired a direct ignition relay supplying power to the coils and cleaned up some wiring (including rewiring the field coil and investigating stator wiring). One issue i've been having is that when I turn the ignition on (but not started) i'm getting a fairly big voltage drop even with lights off and bulbs unplugged. Roughly between 0.75V to 1V once it settles out. If I unplug the regulator it climbs back up maybe 0.4V, but I would assume that's due to the voltage required to magnetize the field coil (of which it is magnetizing quite effectively). As well, the rectifier tested good for open one direction and some resistance in the other, but what is considered proper resistance numbers? Mine were still high, around 400 M ohms, but i'm not familiar with the operation of diodes and what's normal or not.

Two things of interest that I have yet to properly interpret
1. Measuring voltage between the battery and the brown wire going to the regulator gives me roughly a 1 volt reading
2. When running the engine, the reg works great, i'm charging no problem and it's properly limiting voltage, but it's limiting it to ~13.5V instead of 14.x V measured at the battery.

I ran down the line of checking voltage down the main power line, and this was an issue of major voltage drop before the ignition relay so I don't suspect it being the culprit. If a there was a dirty connection at some point in the line, could it "fool" the regulator into thinking it was putting out a proper 14V at 4000rpm when it's somewhere south of that, around 13.5V or lower volts? I've tried to interpret the wiring diagram, but would it make sense that the voltage "leak" would be after power leaves the regulator and before it hits the battery?
 
What does the voltmeter read when you are going down the road at 4000rpm?
Also be aware the cheap multimeters can throw off numbers by quite a bit. You may be right where you need to be.
 
I don't recall exactly but mine does drop around a volt with ignition on but motor off.

The rectifier sounds good. It's a semiconductor so there is no "right" resistance value.

The regulator is unfortunately enough powered by the same wire it senses from. Other regulators have a sense wire that senses at the ignition rather then further down the line at the regulator.

I wouldn't worry too much about taking readings while the bike is off. You'll have no point of reference since there are no standard tests to compare what you're seeing to.
Check for appropriate voltages at the RPMs specified in the manual.

Go through the wiring harness. Clean all the old connectors. Pop the terminals right out of the plastic connectors if you can.
Also clean all the old fuse holders. Maybe think about switching to automotive blade fuses of you haven't already.
 
Thanks for the replies.

I have switched to an automotive blade fuse block.

Another question to throw into the mix: besides doing the old "contact cleaner down the slot and turn the key a hundred times", is there better way to clean or disassemble the main key contacts? I'm not getting resistance measuring across the soldered connections at the back, but it's intermittent when the bike is vibrating then maybe that's a problem
 
You can take the ignition switch apart and get it all clean. It's pretty straight forward when you see all the pieces.
 
If I recall your bike is a bit of a mix of models?
Which year is the ignition switch from? The later models at least can be fully disassembled pretty easily.
Haven't done my 360's ignition switch yet.

Oh, just double-checked the voltage measured at the battery and it immediately drops about .5 volts with ignition and kill switch on.
 
Everything except for the actual engine block is a 76 360, including the original points ignition. So are you getting a 0.5-1V drop between the battery and the sensing wire (which is actually black with a red stripe and not brown on my bike, unlike the very helpful rewiring writeup on the site)? If it's just an idiosyncrasy in these bikes that it reads without draw from anything, then I can live with that
 
Seems to running alright now. At 1000 rpm idle it loses charge slowly, but 2000 rpm and it seems to charge reasonably. I would definitely recommend a direct ignition relay to anyone having weak spark issues also. My spark went from a fairly thready yellow spark to a fat blue-ish white spark with it. For the cost of a waterproof relay and an inline fuse I think it's a pretty easy upgrade.

Here's a shot of my bike now that it's back on the road
IMG_20170325_195412.jpg
 
Looks fantastic. I love seeing the original paint job and decals in good condition.

My 360 was doing the same thing. Not charging well, losing voltage, misfiring when the coil voltage dropped too low, and then not revving up again after stopping at red lights.... Made for a few awkward moments trying to pull away and not going anywhere.
The ignition relay seems to have helped a lot.

I don't have my meter at home to check voltages. Will try to remember to bring it home for the weekend, if I'm not pulling over time at work.
 
Ended up changing my battery and the issues were solved. Just in case someone else is holding out on it, it's often the obvious things we overlook
 
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