28HP Johnson electric start motor

[LymanLou]

Hi,<br /><br />While most of the electric wiring for the motor is obvious, there are 2 black and one red wire that going into a connector in the solenoid box, which then run to various places on the motor. Are all these just switched to on when the ignition switch is turned on? Are any of them to be held high all the time? Are any of them return wires, or are they all hot? Any help would be much appreciated.

 

[Paul Moir]

Re: 28HP Johnson electric start motor

Got a model number or approximate age?<br /><br />If this is the '60s one, I would say that the red one is for the choke solenoid and the two black ones are for the kill switch. The kill switch connects these two wires together to stop spark. When the engine is running normally, they do not connect to anything. Do not connect these to +12v ever.

 

[LymanLou]

Re: 28HP Johnson electric start motor

Hi Paul,<br /><br />Sorry I forgot to give the Mdl. number it is an RX-11A SN 2378506. So the black wires have a source, and if the voltage is removed, a relay drops out or some such thing? Wow, I did not think this old a motor would have had electronic choke, is it on a timmer, or do I wire it thru a switch back to the source so that it activates the chole when the switch is closed? <br /><br />Thanks again!

 

[CATransplant]

Re: 28HP Johnson electric start motor

There shouldn't be any voltage to the black wires at all. You should never allow 12v to touch those wires, or you'll be shopping for new magneto coils!<br /><br />The black wires' function is for the kill switch. Normally, they're connected to the M terminals on the ignition switch. They're what shuts the engine down when they're shorted together by the switch. Keep all 12v positive away from them.

 

[CATransplant]

Re: 28HP Johnson electric start motor

You'll see the choke solenoid attached to the carburetor. Check for continuity between the connector on the solenoid and the red wire you found. If there's continuity, that's the choke wire.<br /><br />If your ignition switch is a push-to-choke switch, you can connect the red wire to the C terminal. If not, you can wire a separate pushbutton choke switch which will supply 12v positive to the wire to activate the choke.<br /><br />Again, though, be very careful not to power the two black wires.

 

[Paul Moir]

Re: 28HP Johnson electric start motor

The important thing to understand is that the outboard's ignition system is self-contained and totally independant of any battery or whatever. It generates it's own power, and shorting out the wires shorts out the ignition system's points. (Points are little switches that are activated by a cam on the crankshaft to time spark).<br /><br />If you click the little 'Man-Next-To-House' icon at the top of my post, you'll see my '62 RX-10. The transom bracket is actually from a '63 RX-11.<br /><br />I drew up a schematic for 28hp engine. If you want a copy, email me at paul.moir@ns.sympatico.ca<br />And if anyone knows where I could host this small PDF file, please let me know.<br /><br />EDIT: Never mind, it's still online:<br /> http://files.filehosting.org/pr12156.pdf <br />Ignore the generator and the regulator + fuses on the right hand side if you don't have a generator.

 

[LymanLou]

Re: 28HP Johnson electric start motor

Hi,<br /><br />Thanks a lot! Ok, knew the black leads had to have some source, did not realize it was motor generated. The start switch does indeed have a push to choke feature, but there is a newer motor on the boat now, and I was not sure if it was for that motor, or the original.