Jet Boat Update 3/1/2024

I finally heard from my friend in Oroville that he was well enough to do the boring on my Evinrude 150 HP Cross Flow Powerhead. The only condition was that I had to be there to do the lifting. Bob was still not supposed to be lifting engine blocks onto his boring bar. We got the three bad cylinders bored and he went on the do the honing on all 6.

Once I knew how far we had to oversize the bores, I was able to order the parts from Offshore Marine. Ron helped me get the right pistons in the kit. I needed 3 .030 oversize and 3 .020 oversize. I went with WSM pistons again. The parts box arrived and I weighed the pistons. they were all pretty close in weight, but there was one piston that was about 5 grams heavier than the rest. I weighed all of the wrist pins and mixed and matched the pins and pistons to get them as close as I could. I got 5 of them within about a gram of equal. I put the lightest wrist pin in the heaviest piston and still was about 3 grams heavier than the others. I decided to remove a bit of weight from the one outlier. I used a cutter head on a Dremel tool and removed some material from the bulky areas on the sides of the pin bosses. I took off about 3 grams of material which brought the heavy one down to about the same as the other 5. I had contacted the piston manufacturer about the heavy piston and they told me that it was not a worry. They actually chuckled "that old crossflow does not care about balance" Just put them as is. I mostly accepted that advice, but I did want to get that one outlier back to similar weight as the other 5.