1985 250R and 1986 Tecate 3 owner here! Also a pristine 87 Fourtrax!

[ps2fixer]

Yea, regulator requirement would be because their stators are higher output.

Was it only the headlight bulb wired in? What was the wattage of it? The wire diagram says 50w and the taillight is 8w. I don't think a 50w headlight would blow in the system quite that fast if it was the stock stator. How was the regulator wired? The old school 2 wire style basically dynamically adjusts the draw to keep the voltage under a set value and generates heat as a byproduct. Maybe it's blown or has a bad connection.

The part number you listed is for a machine with a battery and looks to be 3 phase, pretty sure that's the wrong part.

This is the style of voltage regulator I'm thinking about where one lead is on the power and the other is on ground.
https://www.ebay.com/itm/1985-Honda-...hamKke&vxp=mtr

The other one linked above has the power run through the regulator, so you have to tap into the power output early, and only connect the rest of the harness to the output to keep it isolated (4 wire design). 5 and more wire is similar but for different alternator designs.

It probably would be best to get a multi meter to test things better.

Since you mentioned you have a 250r regulator, I looked up the wire diagrams for it, and looks like 85-86 were the only ones that had a regulator and is the 2 wire design like the 350x one I linked above. It also states it's an AC Regulator, not 100% sure if it would work with DC, could be part of your problem? Here's a page on how to test the regulator on a 85-86 atc250r. I suspect the voltage test would be done with the meter set to AC. You could test at the headlight plug with the lights turned on with no bulbs hooked up to test the voltage while running. In the service manual they are basically testing the light power wire going to the switches.

It might be worth while testing w\o the regulator hooked up to see what your base line is and see what voltage you get DC vs AC testing.

[ironchop]

Does that part support AC and DC? Like the 350x is AC, the Tecate might be DC, I'm not sure. Based on the wiring, it works with a single field (single phase I guess) alternator, a 3 phase one would require a different regulator, but then again those really only show up when the machine has a stock voltage regulator.

I thought I recalled reading on Kawi forum that the Tecate lighting coils were AC so that's why I figure he needed a rectifier with the regulator and suggested that one.

Again, I could be wrong

Sent from my Z958 using Tapatalk

[ps2fixer]

On the rectifier, light bulbs are more or less not effected by AC vs DC if the right voltages are used. The 350x headlight bulbs I use are for road bike application, so they are DC 12v (well up to around 14.6v dc). Batteries on the other hand won't charge off AC, but a simple diode works for them to charge though.

Based on what I've learned lately with the Goki starter kits, the 350x puts out around 14v ac with the regulator working, but when I force the power though a diode, I got about 1/2 the dc voltage than expected on my meter. I guess when DC isn't solid power, meters do weird things like average the voltage out over a small amount of time. I had to run my meter in amp test mode to validate power was going to the battery, which I got 2.5amp draw with it running, so it was working fine. Just some of my experience with the weird world of ac vs dc on these machines. Here's a fun diagram that's a little more deeper into electronics. Basically the AC power when converted to DC though a single diode will only allow the positive power going though, when it reverses the diode stops it. There's also a diode voltage drop that happens on the DC side too ~0.7v if I remember right.

[bryank30]

Ok. I just bought a 80 watt 100 watt headlight bulb. Problem silved? Chime in guys

[ps2fixer]

You have a multimeter right? No point burning up more bulbs, we don't know for sure what output the alternator is, so adding in a regulator would probably be the best idea to cap the max voltage.

[bryank30]

Yes I do. How do I need to configure it to read watts?

[ps2fixer]

Depends if the multimeter can handle it, 100w/12v = 8.3 amps, if the voltage is say 15v, the math works out to 100w/15v = 6.7 amps. Some multimeters can handle 3amp max, 5amp, or sometimes higher. Mine says 10amp max. If you go over the rating, you'll blow a fuse in the multimeter. The alternator keeps putting out more power the higher rpm it goes, so I'd suspect you'd have to get a reading with it red lined to get max output, but there might be a prime rpm it puts out most power. I haven't dove into power generation quite that far to know for sure.

I don't think you can get super useful numbers with a meter like this, but maybe, I've never tried. Generally you're testing how much load is being used, not how much is max possible. Another option is to throw a 10 amp fuse between the head light plug and the 100w head light and if it powers on w\o blowing the fuse, it's atleast close to safe and you could get measurements while the headlight is in use to see how much wattage the light is using.

Anyway, each multimeter is a little different, but mine has 3 lead plugs. Center one is black/grown which isn't moved ever, but the red lead in it's normal test mode spot is for voltage, ohms, and very small amp readings (0.4amp max). To get to the higher amp side of it, I have to unplug the lead and put it in the other hole which is only for high amp testing. The amp test on mine is labeled mA/A for milliamp/amp. Generally the amp test puts the multi meter in line between the power source and the load (generally a bulb in this case). Not too sure if you'd want to short out the power/ground though the multimeter, the alternator might get overly hot from it being a dead short, so in my mind you'd still need some sort of load. I'd guess the 100w light bulb work be high enough to handle idle rpm to get a basic readings and if there's head room to go higher, push it to a higher rpm and watch the numbers. If you go over 9-12amp the bulb will probably blow depending on the voltage.

Now the funny thing, the regulator would be a perfect load since that's exactly what it's designed for. It should have circuitry to limit the max voltage, but I could see it being a simple high wattage resister which might not be a low enough resistance to put enough load on the higher wattage alternator. Getting hard numbers would tell more of the story though.

I know this electronics stuff can get confusing fast, it gets a lot worse when you get into circuit board stuff and current directions in diagrams vs actual true flow etc. You could always just try the 100w bulb and see if it blows, a fuse could protect it from major over powering, but fuses are based on amps, so the voltage would have to be guessed and I think a 10amp fuse is a little high and a 7amp is too low for the 100w load at the variable voltage 12-15v.

[bryank30]

PS2 Fixer. Thank you for the advice. I'll get a inline fuse holder and try that.