Breaks acting as engine kill switch

Hi! I am the proud. New owner of a 1980 concord shadow with a minerelli v1 engine. When I first tried starting the bike, the engine would start but when I hit the breaks, it died. I was advised to remove the break light switch plugs and tape them together. This fixed the problem. I replaced the break light switches (thanks treatland!) but when I tried starting it, I couldn’t even get the engine to turn over. I have tried replacing the rear bulbs and still nothing. Obviously, I would like to get the break lights working again for safety purposes. Does anyone have any experience with these types of problems?


Re: Breaks acting as engine kill switch

I failed last week on city bike with a minarelli and ext ig ground tried forever and got nowhere.

1. have the right switches, normally closed?

2. the switches are not grounded to body? from switch terminals to ground.

3. Is the tail light grounded good?

wiring is pretty straight forward. from ground to one switch to the other switch and all the way back to the rear brake light bulb.

sadly, I couldn't figure it out.

Re: Breaks acting as engine kill switch

Maybe you installed the wrong switches or possibly reversed the wires ?

Re: Breaks acting as engine kill switch

By the way , it spelled BRAKES .

Breaks are what you take during 'exercise' . ;)

Re: Breaks acting as engine kill switch

Mine works like this:

Black wire from engine to taillight side of bulb (the dimmer side.)

Ground wire attached to taillight side of bulb, to frame ground. (So black wire and ground wire attached to same side of bulb, dim side, always on.)

Brake switch wires: one goes straight to brighter side of bulb. Other spliced into black wire at engine. No ground.

Had dual switches, one on each lever, but one switch failed. When it worked, the switches were wired:

Front brake switch, one wire straight to bright side of bulb.

One wire from front brake switch to rear brake switch.

Other rear brake switch to black wire on engine.

No grounds in switch wires.

The rear lever switch on mine failed. It was old and crusty. Pulled both wires off rear brake lever switch and taped them together, so brake light work off front lever only.

So basically, ground taillight off power side, don't ground switches.

Re: Breaks acting as engine kill switch

it depends if u have ext ig ground or not which the op hasnt noted.

Re: Breaks acting as engine kill switch

Do some V1s not have an external ignition ground? Mine all have red (to positive coil, points, kill). Blue (to negative coil, ground) and black to power.

Re: Breaks acting as engine kill switch

Rosa, Pat, do you have a resistor in the taillight assembly? That is sometimes the culprit.

Also, it sounds like you may have put the wrong switches on, normally open vs normally closed? I’m trying to remember which ones Cimatti takes...

Re: Breaks acting as engine kill switch

sounds awfully like the ignition ground is through the brakelight, and that's not working for the above mentioned reasons such as fault in wiring, switch, brakelight or resistor.

Essentially the way those work is the brake lights are powered through the ignition coil's ground. When running and brake levers released, they pass the current directly to a ground (normally open switches means when the button isn't pressed, it's open circuit - kinda confusing because "normally' when youre not pulling the brakes, the button IS pressed, so it's closed circuit til you pull the lever)

so then the way it works is normally brakes released, current is closed and passing to ground and the ignition is grounded and the bike runs. THEN when you pull the brakes, it opens that switch, and the power dumps through a parallel wire to the tail, and grounds through the brake light - and still runs. this lets the brake be brighter and not dim the running lights.

Well! if the taillight's burned out (most common issue of this sort) it can't ground through the brake bulb, and so the igntion is ungrounded, no spark, bke dies.

you can test this by holding the brake and checking for spark. you can also test it by directly grounding the ignition wire that normally goes to the brakes, or by bypassin the brake switch (connect the 2 wires directly) so it never goes open. that'll make the brakelight nonfunctional but it will run even when braking.

The simplest solution is usually replacing the taillight bulbs. but it car rear up if the bulb burns out, and leave you with new troubles so the most RELIABLE solution is to just ground that wire so it always runs. Then if you wanna restore brake light functionality, you've gotta get a normally closed brake switch and run it parallel off the headlight wire. the headlight might dim when braking but this is a simple reliable solution employed by most other mopeds. Or jsut use hand signals cuz a ton of mopeds dont even have brakelights anyway.

Re: Breaks acting as engine kill switch

^^i think u got the n.c. n.o. mixed up. Unfortunately, the cimattis gone, i literally rebuilt the motor in less time than i spent on trying to fix the brake light, frustrating.

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account