Re: New (old) stuff
A 66cc should always have more torque than a 48cc so theoretically it should always accelerate faster. Given the compression ratio would be the same and the ports be in good condition on both. I have seen extra casting on the inside of the ports before that partially blocked so I could see the performance being slower on one engine due to that. In the very top end the 48cc theoretically could go faster than the 66cc due to being more balanced, but wind becomes a huge factor in that and being able to have enough power to maintain acceleration to the point where the 66cc is unbalanced and having a hard time accelerating due to that and wind factor.
I'd love to see a 48cc keep up with a 66cc, but I think if it does the 66cc has a couple things that need adjusted on it or the 48cc is modified.