Re: 80’s/90’s 50hp opinions?

[DAN ANDERSON]

First off the first motor with the new replaceable sleeves is a 1980 60hp. These motors are referred to as 45 cu. in. motors. (44.9 actual) Talking about two cylinder engines here. OMC earler and later made a three cylinder 55hp and 50hp.
The 45 cu in motor was built in 40,50,60hp models as well as a 48SPL (just a 50hp without VRO or any other features). The 60hp was dropped when prop rated hp motors came into being.
Comparing the older motors (pre 1989) can get you in a lot of trouble. The motors look the same, but several things changed. First off and the biggest that will give you trouble is the gear shift boss on the bottom of the powerhead. When building powerheads and buying scrap blocks we had to keep an eye out for just what we were buying. You can’t get around if the wrong boss block is attempted to be used on a model engine it wasn’t designed for. The commercial engines get into this because of the different gearcase. There are other more subtle differences (mounting bosses for electrical items). Those could be worked out, but not the shift mechanism with out major work or possibly swapping front halves which I don’t consider a proper fix.
As far as the power differences from model to model, OMC/BRP will do that with carb differences when possible. The easier/simpler/cheaper the better. Usually it is carb throat/venturi size. The sleeve is the same for a 40/50hp motor. As far as it being put not matching the aluminum ports, that happens everyday with all manufacturers. That is not by design to limit horsepower, although it certainly does do that. Sleeves also move from time to time, especially after an overheat. Keep in mind the only thing that holds those sleeves in the block is the machined fit. The factory does not put the sleeve in as tight as rebuilders do. (Ease/speed of manufacter)!
I was lucky to have worked for OMC for 25 yrs and then worked at a rebuilder/parts distributor for another 5yrs. I got to see both sides of how they said it was done and how it got done, by all the manufacters. We sleeved/bored about a 1000 motors a yr. during my tenure.

Dan in TN