Ok, here's a (rare for me...) success story...
I bought a 1975 Johnson 115 hp with a jet and controls from Craigslist for $300. I figure the jet is worth that so I drug it home. The guy said it started running rough last season so he simply repowered his boat instead of messing with this 30+ year old motor.
It had good compression and appeared really clean so I was getting optimistic . I cleaned up the carbs and put new spark plugs in it and it ran like a champ in my garage! Water pump looked new as did the sleeve and impeller.
We have been running a 17' Alumaweld Sea dory (semi-V) for many years with a 1991 70 hp Johnson prop which was a good combination and got about 30-35mph out of it. We put a jet on the 70 this year, and while it worked so so, I wanted a little more "get up and go" from it. So....Saturday I made the swap to the 115.
I took it out on Cottonwood lake with two of my young daughters and got 34 mph!! The motor initially coughed and sputtered a bit until it cleared its throat, then it purred like a kitten! We took it out again today with 3 adults, 3 kids, and a 100# German Shepard (estimated 900 lbs total) and still it jumped up on step and topped out at 30 mph (per GPS).
Now I just need to find a 18-20' jon boat hull to put the 70 on!
Anyway, just had to brag about my cheap setup a bit. If you see a blue Alumaweld with an old Johnson 115 cruising the Deshka or Little su, it is probably me . Wave me down and say Hi!