swapping a 1981 35hp johnson with 1964 28hp, will it work?

[akukulya]

i have had many problems with my 1981 35hp johnson seahorse (right now it doesn't work under a load). I have a working 1964 28hp which I would like to swap it with. It looks like the '64 has no solenoid and I am not sure if I will be able to wire my working wiring from the '81 into the '64 vintage. Is anyone familiar with wiring in these two engines and if it's possible to do this? <br />1964 super seahorse model # rxl-12m<br />serial #j2432273<br /><br />Thank you!

 

[Paul Moir]

Re: swapping a 1981 35hp johnson with 1964 28hp, will it work?

pescadora - there's a few significant differences between the 28hp and 35hp wiring regarding the kill switch and the start circuit. Also, the 28hp likely has no charging system. If it did, it would be a generator connected by a toothed belt to the flywheel.<br />Since the solenoid is included under the cowl of the 35hp, but not the 28hp, you'll need to purchase a marine solenoid and install it in the boat. Basically, the starter wiring works as follows:<br />1) Attach the large wire from the positive battery post to one of the two large lugs on the solenoid.<br />2) Attach the keyswitch 'ignition' wire to one of the two small lugs on the solenoid. This wire ought to be yellow with a red stripe.<br />3) Attach the large wire from the starter on the outboard to the other large lug.<br />4) Attach the other small lug on the solenoid to the saftey cutout switch on the engine. This ought to be a white wire. The cutout switch is a microswitch that's clicked off when you advance the throttle past about 1/3.<br /><br />As for the kill switch wiring, there ought to be two small black wires coming from the engine. Terminate one (wrap it up with electrical tape), and attach the other to the black/yellow stripe wire from the iginition switch. This'll only kill spark in one cylinder, but that should stop the engine when it's reved down.<br /><br />The choke solenoid then needs to be wired up. This is simple - just attach the yellow with black stripe wire from the ignition switch to the engine's choke solenoid wire. It ought to be red with a white stripe.<br /><br />The large black wire that attaches to the base of the starter bracket gets connected to the negative terminal on the battery.<br /><br />Unless you're using tiller steering, the steering mechanism is just about completely different.<br /><br />Hope this helps!

 

[akukulya]

Re: swapping a 1981 35hp johnson with 1964 28hp, will it work?

Paul,<br />your suggestions are incredible. I'll follow your directions and hope for the best.<br />Many thanks,<br />Amy

 

[akukulya]

Re: swapping a 1981 35hp johnson with 1964 28hp, will it work?

ok, I have installed the solenoid and attached the positive battery post to one of the large lugs (does it matter which one?). <br />My wiring from the keyswitch consists of four connected wires: 1. red wire for battery...would this be the ignition wire?<br />2. white wire for choke<br />3,4 are black wires labled 'M' (are these both ground?) and i'm not sure where they go on the engine end.<br /><br />I have attached the large wire from the starter to the other large lug.<br /><br />ON the engine end there are only a total of three more wires. One is a white wire going into a terminal at the top of the flywheel and onto the fuel vacuum. (is this the safety cutout switch?) and does it stay where it is with an additional wire lead onto the small lug on the solenoid?<br /><br />then there are two black wires from the kill switch. both wires are terminated and one goes to a terminal on the engine block and the other goes to the fuel vacuum. Which one needs to be attached to the ignition and does it go to one of the two black wires labeled 'M'?<br /><br />Which wire is the choke solenoid on the engine? I'm not seeing it.<br /><br />I have it wired and am reading 12 volts across the solenoid but I get nothing when turning the ignition key. What wires allow the the voltage to open and close across the solenoid? <br /><br />I know I am close, just need a little more guidance. Thank you!

 

[Paul Moir]

Re: swapping a 1981 35hp johnson with 1964 28hp, will it work?

Just a simple description of the solenoid:<br />When there's 12v across the two small lugs, (Doesn't matter which way) then it clicks and a large current can flow through the two large lugs to the starter (Doesn't matter which way).<br /><br />The white wire on the engine - if this is tied into the base of the vaccum cutout switch (which is different from the saftey cutout switch), and goes from there to a little switch just underneath the flywheel, then this is to be connected to one of the two small lugs on the solenoid.<br />If the wire goes up into the plate underneath the flywheel which turns when you turn the throttle, then there is no saftey cutout switch present. So Connect one of the small lugs on the solenoid to ground instead (negative on the battery).<br /><br />If the red lead comes from the 'S' terminal on the keyswitch but not the 'Batt' terminal then attach that to the other small lug on the solenoid. <br /><br />At this stage, with the throttle set to 'Slow' and the engine ground connected to the battery's negative post, you should here a click from the solenoid when you crank the engine. It should not click if you have the throttle set to 'Fast' if there's a safey cutout switch.<br /><br />Now, for the kill switch wires, which are a completely seperate circuit from the starting wires. Connect each of the two black wires labeled 'M' to each terminal that the kill switch on the engine is connected to. That is to say, one black wire should go to the center of the vaccum cutout switch, and the other should go to the terminal on the engine block. It doesn't matter which to which.<br />Check to make sure the two wires labeled 'M' are connected to the 'M' terminals on the keyswitch.<br /><br />If the 28hp had it's electric start retrofitted, it may not have a choke solenoid. If it does, it's a cylinder about the size of a film canister strapped to the bottom of the carburetor. The sole wire attached to the screw terminal on it ought to be red. It would directly attach to your white wire.<br /><br />I hope this explains it. <br />If not, please feel free to ask for clarification!