Tzed, let's say your theory is right, what exactly was done wrong that caused the ring to hang in the transfer port ? What should have been done different ? How are Brad's port mods more radical than what is routinely done on race saws ?
I'm just trying to learn.........
I think I'm going to have to add "Tzed is right" to my signature line, because he just keeps making sense. And how can you argue with someone with such a clean cylinder?
I can't see the top of the piston shearing off without a ring having caught to generate that force. The extent of the damage might have to do with casting issues, but I am convinced a hung ring is the root cause.
The transition on the top of the intake port is more square than I would like, but looking at where the blowout occurred on the piston, the intake isn't an issue.
Brad didn't actually answer your question of intake width, but assuming a width of 65% of bore diameter, and a 90 degree split between the pins, there is a little more than 2.1mm of cylinder wall between the edge of the intake and the pin. Looking at the pic that shows the separation between the intake and the transfer, Brad's conclusion that the end of the ring didn't make it into the transfer port seems to be valid.
So what caused the ring to hang? I would say the widened portion of the port was much too square. The pic might exaggerate this, but that profile would make me nervous before the piston cratered. The damage to the transfer appears consistent with this.
Widening the transfers can improve scavenging by decreasing velocity, but only if the flow remains symmetrical. I wouldn't widen transfers without some means of examining flow. From what I've read, it'll take the peak down a little and give you more in the middle.
If your intentions here are what you say they are, you'll drop this and let the thread continue.
If your intentions here are what you say they are, you'll stop lashing out when you get answers you don't want to hear.
If you give all opinions equal weight, you'll never have an answer.
