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582 electrical system question

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2 months 2 weeks ago #22420 by knfevg
582 electrical system question was created by knfevg
Hello Everybody.
It's very nice to join the forum !
Not long ago I became an owner of an interesting device. It's a 1995 Tomcar TM12 buggy, Israeli made. This buggy runs a 582 Rotax, thus I'm in this forum :)
The motor that I have is somewhat alive: it runs and gives a good compression (120 psi). I'm in the process of building conrod bearing clearance tester to check the status of the bearings and if is alright, I wont be doing an overhaul at this point (the rotary valve oil looks OK so I hope the seals are good). I will rebuild the carbs (ordered the rebuild kit for them) and will change all the hoses that I can (oil hose, fuel hose, etc).
As I'm looking for a clear installation, I'm trying to understand how things were supposed to work in the electrical system. On my motor, the loom that comes out of the magneto is all wrapped in electrical tape and plastic ties. I want to remove the tape and make a nice loom with spiral hose, soft tape and proper connectors. Could maybe someone share a photo of how the original loom looks like?
I also have a question about the shortening cables (the cables that are used to stop the motor but disabling the ignition). In the manual it says that the cables should be left open ended while the motors runs and pulled down to gnd to stop it. On my setup, for some reason, the wires were left open while running but PULLED UP to +12v to stop the motor and it worked. How is that and what would be the proper way?
Thank you
Evgeny

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1 month 4 weeks ago #22617 by Bill Hertzel
Replied by Bill Hertzel on topic 582 electrical system question
The spark happens when the Points Open and the Magnet field in the spark Coils collapse.
Traditionally the Points are shorted to ground producing a virtual set of points that never open. No Spark!
Anything you do to prevent the opening and closing action is going to stop the engine.
Making an engine NOT Run is generally easier than the alternative

Connecting the Points to +12v will stop the engine but it will also produce a dead short of the power source through the points to ground.
Unless there is some current limiting device (Resistor?) in series with the ignition switch, the alternator and battery are going to be shorted to ground. Bad!

Even with a current limiting device in place, unless the ignition switch is OPENED soon after the engine stops, the battery is going to be drained in a short time. Also, Bad.

Connect the Ignition switch to ground.
Connecting to 12v will stop the engine but that is the only good thing that can be said about that configuration.
Bad for the Points. Bad For the Battery.

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
whertzel1@yahoo.com
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The following user(s) said Thank You: knfevg

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