The parts came from a Honda GX25. My guess about the pistons is that Honda has more than one supplier. There’s really not much of a dish in the two you see.
I'm working on a V4 engine I designed. The crankcase is a weldment but the rest is made from solid on manual machines.
It will be fueled by gasoline or propane but I'm not sure which way to go. If it runs well it will likely power a boat of about six feet long.
I'm not a purist and my machines...
For those interested in the finished boat underway, I finally have video.
It's running on glow fuel and glow ignition in these videos. Blue smoke in the low speed video is due to a low speed miss on one cylinder.
Ray it’s an alcohol carb with a reducer in the barrel. Yes it’s extremely sensitive but I’m not sure what shape another needle should be. Do you have a drawing of a good one?
John