Heated grip circuit.

[rminier]

Long story...I have owned an 83 Vmax for many years. Got it free in exchange for a little work for a guy back in 88 or 89. He told me motor was blown. Once I tore into it I found crankshaft was totalled. Found a used 84 motor with an excellent crank and cases, which I have run ever since. Had a factory 83 service manual which also included the supplement for the 84's. The service manual showed the extra wire coming from the motor stator (on the 84) was for optional grip heaters. I had installed grip heaters on the sled a long time ago, but I tapped into the 12V regulated lighting circuit, since I was lucky to have read somewhere that yamahas use their own heated grips that operate on a higher voltage.
Unfortunately, the 100W output of the stock Vmax lighting coil isn't quite enough to operate the headlights and the heated grips at the same time...you have to choose...no heated grips at night, for sure. About 3 years ago the original C.D.I. went out, so while troubleshooting that problem, I stuck the original 83 stator back in the the sled (didn't help). I remember both the 83 and the 84 coils all read within the correct Ohm specs, and I finally got a used C.D.I. off of evilbay, which solved the problem. Anyway, the sled has run great ever since, and I'm tempted to put the 84 stator back in the motor (I'm sure it's good). Can I use that extra coil on the 84 stator and run it through a SEPERATE voltage regulator, grounded well to the frame somewhere, and use 12 Volt heated grips on that separate circuit, which would now be regulated down to 12-13 Volts like lighting circuits are? I think I read somewhere that Yammi grips are designed to operate off of 18 to 20 Volts, which sounds like the typical output of most coils BEFORE wiring into a voltage regulator, and is probably true for that extra coil on the 84's and newer. I'm also partial now to electric helmet shields (Yeah, gettin' old, can't bring myself to try those moto-X style helmets with goggles).
I'm no electrician, but it seems to me that I should be able to use the regulated 12V lighting coil just for the lights, and use that extra coil, wired in WITH a voltage regulator (heck, I have a couple spare regulators) and use it for heated grips and electric shield circuit. ?? Maybe that little, extra coil doesn't have enough output to operate both the grips and the shield at the same time, but I can live without the grips. I just don't want to burn up an expensive heated helmet shield.
Does this sound like it will work, or is there something I'm not thinking about?

[Vmax540]

Adding another voltage regulator which is tied to ground/frame would defeat trying to isolate that circuit from the rest. I personally would use the hand warmer coil for the grips and use the lighting coil for your shield. Using an L.E.D. taillight bulb would lessen the load on the lighting coil.
http://www.vintagevmax.com/ledbulbtest.html