Nice drawing. The whole idea of oval porting is to get more area without needing to greatly alter the timing itself, and to protect the ring. As the ring bulges slightly into the port when it passes, it is gently eased back into position by the oval.

TEDDYWILKK: If you have a weight problem, find yourself a Kioritz engine of 23 to 30cc. These engines are very light and they scream. I have a 23.6cc Kioritz all souped up that turns an APC 16 x 8 prop at 9000+ and only weighs 2 lbs. 9 oz. ready to fly!

Also keep in mind that when I quote weights here, it is without the magneto, but with my prop adapter/magnet holder. The first thing I do with these engines is lose the magneto!

AV8TOR