Reply To: 1957 RD-18 30HP Electric start install

[Phil Budne]

I hope FrankR will chime in, since I’ve never wired a “big twin”, only an 18-hp (without cut-out or safety switches), like your first diagram (but with the start solenoid in a box, rather than under the hood).

My understanding is that there are a number of variables, and man diagrams that cover some (but perhaps not ALL) the combinations of elements you might put together.

Are you planning on a 6 or 12-volt system?
My understanding is that you can run a 6V starter on 12V, but 12V will burn out a 6V choke solenoid.
You can add a ballast resistor and use a 6V choke solenoid in a 12V system.

Using a key switch or a start button?
Your first diagram shows a key switch with stop (kill) wires going back to the magneto plate.
Earlier big twins didn’t have a kill switch, but you can add it, by drilling holes in the magneto plate (quick disconnect connectors are a big plus here, or it will be hard to take off the magneto plate!)

Here’s a past post with diagrams that may be helpful:
https://www.aomci.org/forums/topic/1955-evinrude-big-twin-electric-diagrams/

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