Finally an update (but I'm not finished yet
). I ran another two tanks through it to take me up to 45 minutes which surely has to be enough! I made two mistakes on it with the last tank though. First I forgot (again!) to hook up the pressure line after I'd filled it and second I forgot to close the throttle after I'd primed it. But no drama, one flick and it was running in a 2 stroke for a few seconds while I reconnected the line
After the second tank I did the usual with the degree wheel and the pinch began at 40 degrees compared to the 45 I'd been getting before. I have the impression the pinch is less than what it started with but is still about the same as my Rossi which was run in the usual way (although it's done maybe 40 hours). The check for rod wear showed no detectable change. But seeing it was going to be the last rich run I stripped the engine down to see how things were inside it.
On the piston, the only evidence of any wear was the beginnings of the ring you usually see close to the crown. Most of this was on the transfer side of the piston with only a hint of it beginning on the exhaust side. The photo shows the transfer side. There was no detectable play in the wristpin bosses in the piston.
The liner was starting to show signs of smoothing out because the cross hatching was getting faint. One area between the front transfer and the boost port had taken on a very high polish like a mirror.
Now for the rod (and I know it's not one of the squeaky tight high performance engines). It's difficult to show in the photos because of reflections etc but the upper surface of the rod bush is taking on a nicely polished finish while the bottom half still has the original machining marks. This tells me there was definitely none of this "piston jamming in the pinch and the rod dragging it down" going on. In other words, no "compression-tension cycling" of the rod. One myth busted at least
and it came as no surprise to me.
What I intend doing now is to treat it as a new engine and run it in according to the method given in "the thread"
and then strip it down again. But before I run it I'll use whatever prop gets suggested rather than stay with the 9x6 I've been using up to now (which is the prop I would have used). So pick a prop...10x6...11x5...18x18...
I'm having fun here