Awhile back I converted a Ryobi 31cc motor over to prop and it has been doing pretty well on the airboat that I built for it but I have been embarking on getting the horse power up on it. My latest mod has been to ditch the stock back plate and mill one out of aluminum that uses 4 custom reed valves mounted in a V shape like on a motor cycle. This worked well but I need to combine it with some port work. Those of you who have had the cylinder off of their Ryobi have seen the 2 slots that extend upwards from the intake ports. They allow the intake ports to open quite a while before the exhaust ports. My best guss is that this is some kind of makeshift compression release for easier starting. Anybody out there know for sure???? Obviously with an electric starter this is not needed. I have found away to almost completly plug off these slots but am wondering if the compression will go to high without this designed in compression bleed off. What I am going to do is locate the slots position on the outside of the cylinder, then drill and ream a whole into the cylinder at 90 degrees in the center of the slot and press in a pin that will essentially plug the slot. Of course the pin must not hang up on the piston or ring. Any other ideas????? Should boost the power output a fair amount especially on the low RPM end of things. Not an easy mod but for someone with a mill and lathe at home it is pretty easy.

Fastball.