Re: New to me...
I had a 1978 V4 115 HP which was very similar to your motor. Since you did the choke solenoid you may know this, but here is the scoop on warmup and choke.
Low on the port forward engine face at the bottom of the cowling you should find a square control slider with 3 positions. Out is manual choke, center is electric assisted-that operates off your new choke solenoid, in is no choke.
On a cold start either go full choke or use the middle position. Ideally you want the middle position so you can run it from the controller. Put the main control into neutral. Pump the fuel bulb til it's firm or hard. Raise the little neutral high idle lever partway to open throttle a bit from idle. Hold up on the choke toggle control below the key. Crank engine and expect a start. Once started feather throttle to run at enough speed to be smooth, but you don't need to rev the hell out of it cold. Give it enough gas to just run smoothly. While this is happening hold and release the choke control if needed. You probably won't need choke too long unless things aren't running well. My motor was tuned right and it would run on no choke after any start, but before I got the carbs synchronized it needed a little of the mentioned "assistance". Once it's warm check to see if you need to go no choke or middle position. Theoretically you leave it in the middle all the time but that can get out of adjustment.
Your motor was way ahead of it's time. It has 4 ignition coils and 4 carburetors. It's the 2 cycle equivalent of a very high performance Italian car in it's day.
If you want to adjust it get the Factory manual. Or find a motorcyle or outboard guy. The carbs are synched using a vacuum gauge. In the 80's when we did mine I had an engineer buddy with a fast car-dirt bike hobby who did it with a mercury filled tube system. We got everything tuned up in the ignition then went out on a calm day and he synched up the carbs at full speed going across the bay. It was like finding another 1/3 of the engine's pickup. I kept that boat another 10 years and it always outran similar rigs. I don't know what pitch propeller it had but the boat itself was a Glastron 178 SSV which was this butt ugly trihull minivan looking thing. For waterskiing I could take 18 feet of slack, have the driver boot the gas and dockstart on one slalom ski. I weighed 200 lbs at the time.
It's a great engine. It will be fine with an oil ratio of 50:1 and regular gas or 89 octane.
To check throttle operation remove the cowling and stand behind the boat with engine off & choke off (in), have someone put the main control in forward gear and put the throttle all the way open, the throttle plates should open at the same rate and finish perpendicular to the carb bores.
If anything isn't correct, check the carb linkages, they are very logical and they can become disconnected. The person who did the choke solenoid could have misconnected something. It's also possible that when you had your poor power run that the choke slide was pulled out. That would mean everything is fine. I hope so.
Enjoy your boat, and don't be seduced by her speed, go fast if you want but do it smart. Figure out how it handles in waves & chop. It has enough power to accelerate after you have slowed so it's OK to slow some through the junk.
That's a good looking ride.
