The key should be pushed in when cranking a cold engine. As long as the key is pushed in, it will provide extra fuel to the carbs. (choke) To cold start, it, pump up the primer bulb, then push in on the key for 10 seconds to choke it while cranking. Once started, you will have to occasionally push in on the key during the first minute in order to keep extra fuel going to the carbs when cold. After a minute of occasional choking, it should run on it's own. That engine is a bear to start if the choke solenoid is not working or any of the choke/fuel lines are leaking. Your 88 model engine has a charging rectifier only. Once started, you should see the voltage across the battery terminals gradually increase from 12.5 volts upward. Since it is unregulated, it can get up to 16+ volts after running on plane for 20 minutes or so. If your voltmeter still reads only 12.5 volts after 20 minutes, possible that rectifier is not working. Usually when that happens, the tach will not read correctly-if at all. Runing it that way will eventually discharge the battery over time. That engine has two thermostats, one for each head. The stats open at 143 degrees. Engine heads should warm up to 143-155 at idle after 10 minutes of running in summer lake temp water. If one head is heating more than the other, you may want to pull the thermostat housing apart and change both the stats out. (no point in doing just one at that point.) I'd be careful with the mobil 1 gear oil--does is say for marine use? Any marine grade oil is special-a hypoid oil made to mix with water and still lubricate-if the gearcase seals leak somewhat when in the water. Automotive oils are not made to that spec. Follow boobie's comment in post #9. If you found water in the gearcase oil already, likely the gearcase needs to be re-sealed. Best to do that before you do damage to the gearcase internals. Get a gearcase seal kit and put all new seals in it. Since the engine is new to you, consider replacing the water pump impeller. You may not know how old it is and no point in overheating on the maiden voyage. If you plan to reseal the gearcase, that's an opportune time to put in a new impeller.