Headlight issues

[Stickysteve44]

So I just picked up an '82 Heritage Special. The headlight isn't coming on right now. I read that the reserve lighting unit could be the problem. I noticed the speedo and tach lights dont come on either. The wiring diagram looks like they go directly to the RLU.
My question is if they dont come on could that mean a faulty RLU? Does the bike need to be running for them to turn on? Or can I just switch the ignition to on?

 

[650Skull]

Headlight should come on after the engine catches fire........cranking it over and stopping before the engine fires will make the headlight come on without the engine running..........need to turn the key off to disengage the headlight before turning the key on and trying to start again...........it lights up when enough power is generated in the Stater, that trips the safety relay, on the yellow wire cumming from the stater..........

Could be the RLU is causing the gauge lights from not cumming on, could also be a bad connection in the switch or the bulbs are blown........

 

[Stickysteve44]

The headlight doesn't come on when I start the bike. I was just wondering if the tach and speedo light should come on with the ignition in the on position and the bike not running. Could be the alternator. Checked the resistance on the slip rings and it was at 4.1. Could that be a cause of the headlight not working?

 

[gggGary]

Welcome to the forum!
Skull is pointing the right direction and sounds like you are on the right track 4.1 is pretty low.
First, my guess is the gauge bulbs are burned out, that's real common, 'specially if "some guy" ran with a bad or no battery, voltage spikes etc. LED replacements are available the later bikes use bayonet style gauge bulbs. Does the tail light come on? Blown bulbs back there also pretty common. Good ole 1157's Don't rule out ground issues, the battery ground strap can be rotted. Some PO's can really trash a wiring harness cluelessly trying to fix electrical issues. And hey these things ARE 40 years old, rough storage, can create connection issues with various connectors,.soak with silicone or wd spray, THEN open, clean reassemble, all your electrical plugs.
Get a voltmeter on it, tell us what you see off, on, running? If it's still stock ignition, it generally won't run long unless there is some charging going on. The TCI ignition module likes a healthy 12 volts. Sounds like you have seen some of the charging threads. Check your brushes, they do wear and get too short to make good contact with the slip rings. Check all the fuses and the fuse holders, they tend to rot from age.
Good chance you are dealing with the issue that killed the PO's enthusiasm for the bike. But it's seldom hard or very expensive to FIX the charging system if you do correct troubleshooting. Lot of guys get all it's too complicated and go spend $600 on new parts but that's seldom needed. I've done 30 plus charging systems never needed to install an aftermarket, though I AM doing a vape charge/ignition on a custom I'm slowly building. If a new rotor is needed, @Jim here does rewinds, probably the best deal going.
The late model solid state regulators do die from age also. So some time with a VOM tracking down the issue is in your future.
Always helps if we see some pics of the bike helps get an idea of what issues you may be having, plus we just love pics!
Fuse box area, inside the LH cover. Well that's the short list LOL, keep us in the loop? If you go at this right, it'll be worth it....

 

[650Skull]

Check the fuse block and fuse...........the clips that hold the glass fuses loose their tensile strength and often break, and corrosion on the wire where it is crimet to the clips..............

Yea and don't buy, or buy to change, anything before asking on here. lots of tip bits come out of the woodwork and can save you a lot of money or just a different option........Fuse box as an example...........most change to blade fuse's.........their is a fix, and new holders are available and an easy rebuild of the original.........not saying to do that but some like to keep things original........obscure stuff

 

[Stickysteve44]

All the electrical connections are super duper clean. The bike only has 5700 miles on it. I've never seen connections this clean on such an old bike honestly. Even the inside of the tank looks brand spanking new. (Nothing to do with my problem, just bragging) Checked the fuse box it looks great too.

The previous owner did tell me he replaced the brushes a week or so ago for a charging issue. They came from a parts bike he had though. I was only reading about 12.7 volts at 3k rpms. But that was me trying to hold the throttle open, touch the connectors, and try not have the multimeter vibrate off the bike. I'll have my helper girlfriend come hold it for me when I check again today and get back to y'all.

Also, is the regulator rectifier located on the swingarm in front of the back tire? It looks like that's where mine is, but I couldnt find any detailed information on where it's supposed to be.

 

[gggGary]

regulator rectifier located on the swingarm in front of the back tire?

Kinda, the reg is bolted to the back of the main frame tube behind the motor. about 3" x 3" with fins.
The TCI about 5" x 5" is bolted to the bottom of the battery box.

 

[Stickysteve44]

Alright so here's where I'm at. Just rode the bike to advance to pick up a new set of feeler gauges because I somehow lost mine. Battery was at 12.51 before trip. When i got there battery was at 12.4. When i got home it's at 12.21. Looks like I'm having charging problems. So I checked the magnetic field with the feeler gauge. Little to no activity. So time to check the reg/rec. How do I jump the green wire to ground?

 

[Stickysteve44]

Just checked the resistance on the slip rings and it's at 3.4 now.

 

[gggGary]

Just checked the resistance on the slip rings and it's at 3.4 now.

yeah that's a fail.

 

[Stickysteve44]

yeah that's a fail.

So new rotor?

 

[gggGary]

Better is a rewind from @Jim if he has some ready.

 

[Team Junk]

Get Jim to rewind it.

 

[Stickysteve44]

Also, does that mean there's probably a fault in my charging system that burnt it out?

 

[Team Junk]

Would be a good idea to check the regulator and how old is your battery. Weak batteries have killed a lot of innocent rotors.

 

[Stickysteve44]

For the regulator, am I supposed pull the green wire out of the connector to ground it? Then test the voltage at the batt?

 

[Stickysteve44]

The battery is at 12.36 it seems to be in good condition.

 

[gggGary]

It's hard to prove but that's my theory also.
Way too many owners ignore bad batteries even jump starting to keep riding the bad battery makes the alternator work overtime rotor heats up insulation fails windings start shorting against each other rapid cascade failure after that. 40 year old varnish gets brittle also.

 

[gggGary]

Just ground the green brush but if your rotor's at 3.something, you can stop looking. BEST test of a regulator is to plug it into a working bike and check volts. off, idle, 3000RPM.

 

[Stickysteve44]

Gotcha. Well I'll update once I fix the rotor I guess.