i found a displacement calculator on the net and put in the deminsions of the cylinder and stroke and it gave me about the 33cc range i have not seen a ryobi with this displacement just a 31cc but if my understanding is correct the ryan line was bought by ryobi , so leads me to believe that ryan did make a larger engine than ryobi does now, cause this thing is a 33cc single ring 2 stroke long shaft clutch thanks for u guys help, jeff