I really love the 1955 Johnsons, especially the green graphics. The 25hp is a great engine, not much for speed, but plenty of power to do most anything you might want it to do.
It’s kind of hard to post all the tips, opinions, and possible trouble areas here. But we can certainly respond to any questions or opinions you may have about it. The keys to survival are using a good quality outboard TCW3 oil (any of the major manufacturers products are fine ), and mix it at 24:1, which works out to 1 qt of outboard oil mixed thoroughly with 6 gallons of regular fuel. I keep forgetting that most new outboards are four stroke today, so be sure you are using “two stroke oil”! Look for the “TCW3” rating on the container, you don’t need the super expensive stuff meant for the injected modern two strokes. Running the engine without the proper oil mix will damage it within seconds, especially if run at high speeds. Make sure the engine’s cooling system is working properly, remove and replace the water pump impeller if you haven’t already done so. Use the OEM impeller/water pump parts, aftermarket stuff can be sketchy. Overheating one of these engines at high speeds is a great way to wreck/damage it quickly. Keep the lower unit oil full and fresh (any of the major manufacturers gear lubes will be fine, you don’t need the super expensive stuff). Monitoring gear lube oil level and condition is not so easy, like on a car, no dipstick to pull out and inspect. These old gearcases tend to leak slightly, which is OK, provided you change the lube frequently. Running the engine with no/low lube level, or a gearcase full of water is a great way of destroying the gearcase quickly. Check shift adjustments often, especially if you are using remote controls, you are in for big/expensive repairs if the clutch dog/forward gear lugs get worn to the point where the engine jumps in and out of gear.
.
.