A little background. So I had an overheat on my 73 40hp evinrude 2 stroke 2 cylinder earlier this year due to a bad impeller. I ended up doing the old patch job and just honed the bad cylinder out and replaced the bad piston and new rings on both. Unfortunately nobody seemed to care about the tolerances of the piston to cylinder wall and told me to put it back together. I put it back together and got it back to the cottage this weekend. The original compression was 120 on both cylinders but the scored one went down to 112 after the overheat. The new compression is around 130 on the good cylinder and 122 on the bad cylinder with a fresh battery on the starter. The motor started up no problem and continued to do so throughout the day. The motor did sputter back a few times but that could be the low idle setting on the carb or even year old gas. The most problematic symptom was when the motor was pushed to get the boat on a plane a loud squealing sound could be heard so it was taken right back to idle. The motor could be taken to high rpm in neutral with no squealing at all. Also when the motor is revved a bit higher in neutral and then brought down quickly to idle there is some sort of quick clunk noise as it slows down. It should be noted that a driveshaft that likely has a different part # from the original was put in. The splines looked to be very similar(exact?) as well as length but the splines ran farther down the shaft than the original(gearcase side). How interchangeable are these old driveshafts and could that be a possibility for the screeching or is it more likely to be one of the crank/conn rod bearings that I replaced? If I had ever so slightly misaligned the rod cap bearing would that cause squealing? Lack of lubricant? Bearings were new old stock. Any advice would be great.
