I added electric start to a 1956 RD-18 using the following pieces:

Starter bracket – OMC part #376885 – this is a bracket from a 1957 motor that allows the mounting of either a 6 volt or 12 volt starter (they have different mount hole dimensions)
Starter – I used a 12 volt starter #5712N from Discount Starter. There are many other 12 volt options available.
Starter solenoid – Arco SW058

I think (not 100% certain) the electric start flywheel with ring gear is OMC part #580337.

I did not add an electric choke solenoid on mine, but just used the original manual choke.

• This reply was modified 4 years ago by Bob Wight.

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Gary Pasquale

I don’t have the choke solenoid part number. For simplicity on my installation, I just installed a starter push button on the front of the lower motor pan. Here’s a wiring diagram for 18-20-25hp motor that would be the same as what I did. I’m sure someone here on the forum could provide a wiring diagram for a remote key start.

The 6V starter has a mount hole spacing of 2-1/4″ and a 12V starter has mount hole spacing of 2-1/2″. The 1956 bracket has only 2-1/4″ mount hole spacing, whereas the 1957 bracket has 2 sets of mount holes so you can use either a 6V or 12V starter. You can’t bolt a 12V starter to the 1956 bracket. See pic of 1957 bracket 376885.