Hi all,

I've been looking at some Ryobis on the net and I'm a bit confused. Well, I searched for Ryobi simply because it's what I hear most, so I figured it was the common choice for conversions (I don't doubt there will be more powerful engines out there).
Probably, the basic design has been around for many time, so it's kind of logic that not all them are the same.
Some places tell you about single or double ringed pistons; improved (stronger) connecting rod, "compression release channels" (something to make it easier to start?) and other marvels of the modern world. I don't know how much of that can be said to "improve performance"; IMO often design variations are made to make construction easier, cheaper, faster, etc. and not necessarily to make a more powerful (and "thirsty" too) power tool.

So what are the main differences between versions? Is there a real difference in performance with those changes? An older model can be "updated" somehow?
Thanks in advance!