Johno 115 block and 125 blocks

I have a johno 115 (73/74) with a crowned piston, engine still runs, but the crown is off the skirt so probably not too clever (LOL) - I bought it that way! I also have a 125 (71/72 I think) which is complete less solenoid and starter. Question would the two blocks be interchangeable? Could I just remove the blown powerhead and fit the 125 in its place with the solenoid and starter from the 115? The two blocks look the same, ancilleries are a bit different, but not much. If the starter and solenoid are compatable I might just fit them and use the 115 as a donor for parts. Any advice would be gratefully received.<br /><br />Thanks.<br /><br />Chris

Re: Johno 115 block and 125 blocks

There are quite a number of differences between these two engines. The first being that the crankshafts, and driveshafts are dirrerent. The 125 crank will not mate with the 115 drive shaft, the splines are not the same. Second would be a matter of shift linkage. If you are going to make one engine out of two, use the newer 115 as the base. It has tilt pin steering which is much the better, and easier to hook up, the 125 does not. The 115 has magneto CD ignition which is much cheaper, and easier to maintain. The 125 has battery CD, much more exspensive. Making one out of two would take to long to explain here, but you could use the pistons, starter, carbs, etc.

Re: Johno 115 block and 125 blocks

Thanks for the advice. I think that perhaps I will see if the 125 will run using the starter etc off the 115, then take my time rebuilding the 115. The previous owner drove it to the marina with only three cylinders and it was running fine before the piston incident. (He had just finished taking his 9th successive passenger out on the tube so I suspect he never really gave the engine a chance to cool down. It also shows a lack of maint on the whole boat engine combo. It was a cottage boat that sat in the water all summer and in the marina all winter. (Poor baby needs some TLC!)