ok so after installing 40/17 props on both engines, we discovered that one turned at 3650rpm and one turned at 3900 rpm....
suspecting the points and seals that we just replaced, we replaced both on the 2nd engine.
after testing, we discovered that the two props that I have are vastly different!
same engine, testing one prop at a time, we achieved 3650rpm and 3900rpm on the same engine! so what we thought was an engine problem turned out to be a difference in propeller!
So if you're troubleshooting a weak engine compared to the other engine, try swapping the props....
Tyler