Discussion: Brake Light Kills Spark

[spargett]

Hey boys (and gals),

I can dig in and figure this out, but was feeling a little fuzzy on the theory behind what is actually happening. Thought it'd be a great discussion for the forum where some others could learn too.

1. Got a '66 Triumph T100S chopped out. Full loss electrical system with RR and electronic ignition (tits)
2. Bike started dying every time I used the rear brake.
3. Disconnected the spring on the rear brake light switch and she's good to go.

Here's the question: What do you think it causing the motor to die every time that circuit is completed?

[tzienlee]

you need a Battery,...
it's how they were designed to work,....
time after time all I see are people trying to re-invent the wheel by fitting capacitor's instead of battery's and wonder why it don't work,...
seems pretty obvious that there isn't enough juice to power all you are running, so when you put the brake on it takes all the power and kills the ignition that needs a good constant power feed to work well,... drop below a certain voltage and ya pushing,.....
electronic ignitions like a healthy battery.
fit a battery and it will work,...
it's not rocket science......

[farmall]

Hey boys (and gals),

Here's the question: What do you think it causing the motor to die every time that circuit is completed?

Check for a short to ground in the brake light circuit or brake light switch.

If brake light is OK, I'd put a meter on the charging system to verify correct output. A marginal system might die under a little more light amp draw, like a brake light bulb.

I like batteries. Even back in the dark ages of stock Lucas parts and capacitor battery so-called eliminators, I ran batteries too.

[spargett]

Def just a loose ground. Goes to show anything that doesn't have anti-sieze should loc-tite instead. Charging system is doing great.

[Tattooo]

Goes to show anything that doesn't have anti-sieze should loc-tite instead.

Not really, You just need to go over your bike from time to time and make sure everything is tight.......

Glad you found it.....