That somewhat makes sense. If you take a dial caliper and measure the my port width it is .400. If you measure the ports on the two runner cylinder it measures .300 per port.

that means the total port area exposed when the port is exposed is greater on the two runner cylinder by .200 per side. and this is the cylinder that responds to the timming mod to.

the difference in volume is that the single runner ports are way deeper.

sounds like im gone have to do some port experimentation when i get my next ryobi converted and ready for testing. for right now im gona get this one on my plane lol