No Start (Again) but is it the tail light?

Went to start the bike after sorting the oil leaks (well, so for) and no ignition. Got spark with the kill switch. Seems I've had this problem before so I re-read my old thread. Ground was the culprit before.

I also notice the brake light is intermittent. It appeared that when the brake light wasn't working the ignition didn't either. Maybe coincidence?

I took the rear light off to check all the connections. I could wiggle the wires and get the brake light to work. I have one of the Bulbsthatlastforever LED lights. Out of the back of the board the wires loop behind board and out. Even though I put electrical tape on the back of the board (as recommended) it looks like the wires were getting punctured with the solder points through the tape. I put an extra layer of insulation on the board and reassembled.

Bike fired first kick.

I'm trying to figure out what in the lighting circuit would kill the ignition, and I think it's the ground. I just can't figure out where.

Since it's a custom harness I have no one to blame but myself…

swooshdave said:

It appeared that when the brake light wasn't working the ignition didn't either. Maybe coincidence? I put an extra layer of insulation on the board and reassembled.

Bike fired first kick.

I'm trying to figure out what in the lighting circuit would kill the ignition, and I think it's the ground.

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Brake light, or tail light? Tail light could drop the system voltage to the point where the coils wouldn't fire, but the brake light should only affect the system when you're depressing either brake lever. I'm confused (as usual).

Ms Peel had an intermittent mystery ignition cut out I couldn't find til eventually died in my rough yard and tracing stuff lead me to find tail light ground strap had frayed into power terminal. i had to modify tail light back plate to allow same LED kit wires not to rub raw or vibrate apart d/t pinched kinks. I will never over look that area again, among so many others.

I thought I had isolated all of the circuits as much as possible. Perhaps instead of isolating them I should have embraced a single ground like the stock system? If it was shorting I would expect a blow fuse?

Somehow an unexpected ground was messing with the ignition?

Might you have power going to ground somewhere (a short) that is not sufficient to blow a fuse but enough to drop voltage below necessary starting volts?
Is the battery right up to 12.5 volts or above and in good health?

worntorn said:

Might you have power going to ground somewhere (a short) that is not sufficient to blow a fuse but enough to drop voltage below necessary starting volts?
Is the battery right up to 12.5 volts or above and in good health?

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spark-boyer-fixed-t7303.html

Originally I had a loose ground with the same symptoms, which is why I lean towards something similar.

Battery is fresh and fully charged.

The non-working brake light is curious. I also found a loose ground wire at the brake light, but I haven't been able to trace that make to the ignition.

Don't know about yours, but on mine the brake and ignition come off the same terminal on the main switch (early 2 position). That's how I check for good ignition circuit, by pressing the rear brake pedal, plus testing the brake light before a ride. It also won't go on and ignition won't work if my oil feed lever isn't in the right position. Yours may be completely different.

My 650 is wired up same way. It arrived with a severe intermittent stutter and would also sometimes cut right out then be very hard to start.
Wiggling the key back and forth with the brake pressed on showed a flickering brake light. The same was happening to the ignition.
The problem was corrosion inside the key switch. With a new key switch in place the bike has run perfectly ever since.

Try bypassing the key switch with a jumper wire.

Glen

Yeah, I remember now I had to rebuild my ignition switch one day when it wouldn't start and the brake light wouldn't go on. Best way to check the switch is with a voltmeter across the ignition terminals when drawing current. Ohm meter may show fine.

Yes it is the tail light. I installed one of the same tail light units about two weeks ago. I thought I had insulated the back of the board with enough tape, but after a short trip out the bike died on me. I restarted several times after heading back home. Since I had just installed the new assembly I removed it and found that the back of the board had shorted through pin holes in the tape to the metal bulb housing, dragging down the voltage and killing my ignition. I placed a 1/4 inch thick piece of foam between the stop light board and the metal back plate and the problem is solved. Hope this helps you. Craig

champ7fc said:

Yes it is the tail light. I installed one of the same tail light units about two weeks ago. I thought I had insulated the back of the board with enough tape, but after a short trip out the bike died on me. I restarted several times after heading back home. Since I had just installed the new assembly I removed it and found that the back of the board had shorted through pin holes in the tape to the metal bulb housing, dragging down the voltage and killing my ignition. I placed a 1/4 inch thick piece of foam between the stop light board and the metal back plate and the problem is solved. Hope this helps you. Craig

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Thanks! I used a wide piece of heat shrink. It's pretty thick. I was trying to find some old inner tube but will use this for now.

One thing I learned a long time ago when I had my first Triumph it had a short and burned to the earth wire, it melted all my wiring as the power wire shorted out on the earth wire, when I rewired it I made shore my earth wire wasn't in with the main wiring, I run the earth wire beside the main wiring harness and I do this on all my bikes since that time, it is so easy to rewire a bike without all the crap the standard wiring harness has.

I do all my own wiring and with my Featerbed 850 I only have 4 main power wires in the harness, one is the brake light and one is the tail light and of course one red wire running outside the main harness, I have done this since 1980 and have never had any problem with my wiring in all them years even when running a battery, but better now with the Joe Hunt maggie no need for a battery.

Ashley