" Tim, The 50HP Johnson start
" Tim, The 50HP Johnson starting and ignition system are compatable with evinrude electric start motors with magneto ignitions (up until late 1960s?). However, the cable from the external "starting box" to the motor may be different. While the 50HP motor's cable disconnects, some other OMC motors did not have disconnectable cables. This 50 HP motor requires an external box which contains starter solonoid, and fuzes and connectors for Ignition kill, electric choke, overheat light, and maybe tach. Box also has battery cables hanging out of it. Also the electric box may have a voltage regulator mounted inside the cover, if the motor has a generator. Wire like this: Start terminal of ign. switch goes to plus side of starter solonoid(usually white, but trace it to box). Ign pole of Ign Switch goes to killer wire. Killer wire connects to the only external connector of distributer. You'll need to trace it through box to motor. Electric choke (usually pushbotton on dashboard) goes to choke solonoid, (usually brown, again trace it). You want to use an ignition switch that grounds the ign terminal in the off position. Connect the red wire (should be positive voltage from battery) to batt terminal of ign switch and one side of electric choke push button. Also you will need to have a ground wire connected to the ignition switch. i will see if I can "gin" up a wiring diagram, and email to you. "