Topic: Johnson RDE 16 voltage ? – Antique Outboard Motor Club,Inc

This topic has 9 replies, 2 voices, and was last updated 1 month, 2 weeks ago by crosbyman.

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August 31, 2015 at 9:35 pm #2414
joecb
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Hello all… a friends Johnson RDE 16 , 1954 25 HP electric start… is that a 6 volt system? If so, I understand that 12 V on the starter will be OK but needs a resistor on the choke solenoid .. any info on the resistor needed ?

Joe B
August 31, 2015 at 9:42 pm #22981
chris-p
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Yes that is a 6 volt system originally. The starter will be ok with a 12 volt battery, as long as you don’t crank the heck out of it. As you state though, you will fry the choke solenoid. The easy fix is to simply swap the choke solenoid for a 12 volt one. A wanted ad in the classifieds should get you one fairly cheap. Ill post the wiring diagram made by Frank Robb below.

Ill also post the wiring diagram to run a resistor inline. I forget the exact NAPA part number I have used, but Ill dig it out.
August 31, 2015 at 9:47 pm #22982
chris-p
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August 31, 2015 at 9:49 pm #22983
chris-p
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Here is what I do and swap out the choke solenoid
August 31, 2015 at 9:50 pm #22984
chris-p
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Here is your original wiring diagram
August 31, 2015 at 11:00 pm #22989
joecb
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thanks guys… always good info here

Joe B
September 1, 2015 at 12:42 am #22995
wiscoboater
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Wont 12 volts blow out the starter? I remember doing that to one as a kid. Blew the whole gear assembly off of it. What makes it work with 12 volts so as not to damage the starter? I’m not questioning you guys. I’m just trying to figure out what I did wrong years ago. If I come across another I would like to do it right this time.
September 1, 2015 at 7:37 am #23008
frankr
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12V won’t hurt the starter unless you crank it for a long time. On the other hand excessive cranking time will overheat the starter no mater what. You will find that 12V will crank that motor very easily, whereas 6V will struggle to turn it over. Struggling on 6V will actually overheat it quicker then freely spinning on 12V. In fact, if it doesn’t start & run almost immediately on 12V, something is wrong, so stop and fix the situation.
May 19, 2025 at 7:06 pm #296568
fleetwin
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Here is a parts catalog on ebay:

https://www.ebay.com/itm/335565939435
May 19, 2025 at 8:22 pm #296569
crosbyman
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Canada Member
they have 6 ohms 50 W resistor on Amazon for installing LED tail lights.

JZK 2x 50W 6-ohm Load Resistors to Fix LED Bulb Flashing Signal Error, Turn Signal Bulbs – Amazon Canada

That resistor may very well do the job with 6 ohms and being rated 50 watts it will never burn with a choke coil wired to it in series.

6 ohms will limit current to 2 amps or less since the coil’s resistance will be added in the series cct. Will there be enough volts left for the choke’s operation … possibly…

Joining AOMCI has priviledges 🙂
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