Yours is a completely different Tilt-Trim System than what was used in 1973, and you are correct to use ATF in it. However the previous design used SAE 20 as the fluid.
You cleaned the carbs last year? Did you drain them, or use a Fuel Stabilizer, prior to the Winter Layaway?
When you were cleaning them, did you remove the Core Plugs, especially #5, and get the gunk out of there? Is #38 in good Condition?
Could be a leaky Gasket between the Carb and Intake, and/or a leak between the Intake and the Crankcase. Link and Sync out of adjustment. Low Float Level, bad Gaskets in the Carb, dirt/Gum/Varnish in the carb circuits, to name a few
The Marine Interstate Battery that came with my Boat still had 75% Capacity at 14 yrs, tested at the Interstate Store. It seem to garner a lot of attention from the Staff. I traded it in on a new one, that was 8 yrs ago.
Welcome to iboats
I suspect that engine has an Oil Mixing System, and the Oil is kept in a Separate Tank. I also doubt an Engine requiring the use of Premixed Gas, would have lasted 2 hours if run without Oil
I used the Enertia as a Example as to what is possible with a Blade Design. My Avatar pic, was shot when the Boat had an OMC RAKER, that used to be on my 150 FICHT(had to replace the Rubber Hub to a VP) I don't think the Enertia is made in a size that will fit on a 115hp engine.
If the throttle Plates open too soon, as in not enough Timing Advance, erratic Operation is the result. Most outboards had all the Timing advance in, before there was any real opening of the Throttle Plates, they run fine that why, and it enabled the throttle to be closed once the engine had...
A 4 blade will likely drop the Bow. A prop with more Rake will help raise the Bow. Enertia is such a Prop, actually it will lift the entire Boat Vertically, as well give a completely different feel as to how the boat handles.
