MOPED ARMY

Bump, anybody?

You mean this?

Pretty sure it's just a spade terminal/ground point? Theres a central 4 prong ground point where all the grounds converge up top behind the headlight..maybe its referring to that?

In any case, I don't have a kill switch, and there is no green wire from the ht coil going up to the bars. I just have the blue wire going up to the brake switches, and the yellow/green from the switch to ground

This whole thing is so frustrating mainly because the brake lights were working fine before I rebuilt the bike...only thing different is that I have a non OEM tail light now, and I wired an external condenser...I didnt do anything to change the harness from what it was..at least I can't remember changing anything.

So after looking at the diagram longer I'm pretty sure you're gonna have to get a 6.2 ohm resistor and just solder it in line on the stop light circuit. If you look at the circuit, without that resistor the whole node is connecting ground to the Y/G going to the coil.

With that resistor, you will have a voltage to the coil whereas right now the coil is going to be grounded. You'll then have to un-ground the blue wire wherever it is, cause I think what happens is instead of the stop light circuit (and therefore the ignition coil) grounding with the coil it's grounding wherever you have it which is letting the bike spark but not illuminate the tail light at the same time (since when you illuminate the tail light it connects ground back into the circuit and therefore straight into the coil).

I hope what I wrote makes at least some sense.

I'm gonna post my response to Pm's here for future reference for people who don't have good experience with electrical circuits. This is super shitty napkin math that doesn't account for some things, like the internal resistance of the coil but whatever.

6 ohm is probably close enough to work too if you can find those cheaper. By my shitty napkin math the rear bulb is rated at 6V 10W so it's rated for 1.667 A. With a 6.2 ohm resistor @ 6v you'll have 0.968 A but with a 6 ohm resistor you'll have 1.0 A. I don't see the .03 A making much of a difference to the coil, and 1A is well within spec of a 10W bulb.

How I did the math:

Using the rating of the stock tail light bulb (6v,10W) and the equation P=IV you can find current (I=P/V, or I=10/6=1.67A in this case). You can expect that to be the maximum current in that loop. So on a 6V bike with a 6.2 Ohm resistor, using V=IR (I=V/R, or I=6/6.2=0.968A) you can see that this falls well below the rating of the taillight (and by assumption, the rating for this loop of the circuit). You could plug and play resistance values if you have some resistors laying around to see what the current is gonna look like in that loop. I wouldn't stray too far from spec though, since like I said this is a rough estimate that doesn't account for things like the internal resistance of the ignition coil. (edited)

You're right that I went overboard with my math and shit up there, and I wasn't paying attention and I thought the resistor was in series not parallel. But I think you pointing out that the resistor is in parallel is just proving my point that the resistor is the issue.

Here's a shitty paint drawing I did at work. Current will never flow through the brakelight if the resistor is not there and the wire is shorted.

EDIT:

Actually after drawing all this out and thinking about it you probably just removed the resistor and didn't short the wire, right? So that leg of the circuit doesn't exist. Your shit doesn't run unless you ground the blue wire. The original resistor was also probably grounded to the frame, where the tail light connected to the resistor/ground. You don't have a ground after your tail light bulb right now right? You're grounding it before you hit the bulb and therefore the tail light will not illuminate. If you don't have the blue wire grounded your coil isn't grounded and therefore it won't run.

DOUBLE EDIT: Wait does the tail light work? if so then I'm wrong since they ground in the same spot (edited)

I mean, you're right that I was wrong, that's why I immediately edited it and realized that all of my previous logic was based upon my misreading of the wiring diagram.

In the article you posted: "If there is a poor ground under the rear fender, anytime the brakes are applied the engine will die"

Which is what I was trying to edit the above post to say. Check the brake light ground.

It's getting its ground from the bad ground on the fender. When you hit the brake light switch the ground is no longer in the handlebars, but is instead in the tail light. The bulb is grounding but the coil can't ground through it too because the ground is bad.

Instead of grounding the blue wire to get spark, ground the Y/G and see what happens.

Tonight I'm going to remove the fender and inspect the junction in the harness, hopefully I find my answer there

I have a bag of those secret tail light resistors. Holler if you decide ya want one.

That's a bit overboard I think, surely it'd be easier to check check all the wires in the stop light/ignition circuit

Remove brake bulb and try again to see what happens.

If you dont have a dmm get one and learn how to use it.

Sometimes the switch actual brake switch get goofy and grounds total stupid gremlin. You can test by dissconnecting one side and tying them togetger...work. If not the do the othrr sude. Sorry my fingers r tio bug.