85 Ltd. Electrical Help Requested

[ForedeckYoda]

Hello 1200'ers.

Noob here. Always loved the 85 Ltd., and after she divorced me, got it.
The most beautiful one available (34,000m) has an electrical drain problem and wouldn't start when I put in a fresh battery.

I've got a circuit tester and multimeter and I poke and prod, but I'm more academic and mechanical as opposed to electrical, and I REALLY need help figuring out where to poke and diagnose before I just jump into the surgery!

Q1 - how to eliminate voltage regular as failure point instead of stator?

[Dave-1985-LTD]

Have you done the stator voltage test? I would highly recommend doing so. Should be able to find a detailed post about how to do it.
If you get a good steady voltage on the 3 stator wires, then it should be OK
The voltage regulator on our bikes is known as a "shunt regulator" In electronics a "shunt" is basically a short circuit.
The way things work is this; (In the stock Honda system of that time)
The stator is simply 3 coils of wire that a magnet spins around inside generating a 3 phase ac voltage. About 60vac when disconnected at 3000 RPM
Our LTDs generate 500 watts the standard bikes make 400 watts. once the minimum RPMs have been reached the stator will put out full wattage continuously no matter what else happens.
The first stage of the regulator has a 6-diode bridge rectifier that changes the 3-phase AC to DC.
The second stage feeds that to the bike, and any voltage over 14.1 VDC gets "shunted" to the frame of the bike.
That is how it regulates the voltage, it simply puts enough of a load on the stator that the voltage drops, the regulator keeps it at 14.1 by varying the load (how much power it shunts to the frame)

That's the power generation side.

In our bikes more than any other except the 86 SEI, we have more bells and whistles than the others for many years. there are 3-4 computers depending on what you call a computer.
Our FI computer system is amazing. Honda says to start the bike, buckle your helmet, and go. On the carbureted bikes you pull the choke start the engine, warm it up for 2-5 minutes, then buckle your helmet and go. That is all great as long as it works.
We also have the trip computer with its memory circuits and clock that pull a little power all the time.
Honda says it should be less than 50 ma

This is where things get sticky for me. My bike reads about 44 ma when shut off. but at some point the current goes up and then I have a dead or weak battery.
So I am maybe in the same boat as you, but it bugs the hell out of me because I hold a Federal License in industrial electronics and still can't pin it down.

Make a Google search for GL1200 LTD manuals you should be able to download and look at them. they are too big to print.
I kept searching eBay until I bought all the books on the LTD/SEI

There is a weird bit of wiring behind the battery that I fixed so long ago, I can't remember just what it was.
I just remembered I changed the 3 wires coming out of the stator up to the regulator position, they were very small and burned.

Good luck with your LTD, I am trying to rebuild the entire front end from the head bearings to the tire, then turn it around and new tire and brakes on the back after I check and lube the shaft.