My Ryobi on Gas/Glow does seem to vibrate more than I would like, and more than my other engines. (Also Gas/Glow) I can't say if it vibrates more than it would with the flywheel, because I never ran it with the flywheel. If indeed the Ryobis are externally balanced, a person could run an "out of balance" prop situated to put the weight where you need it in an application that is not using the flywheel. I may have to experiment with that on my Ryobi sometime when I get the time. Meanwhile, if anyone throws their Ryobi flywheel on a balancer, please let me know how it turns out, and if it is not neutrally balanced, where the heavy side is located. Following jrpav1's line of logic, it would theroetically be in line with the crank counterweight when the flywheel is mounted and the keyway lined up.

Let me know what anyone finds out about this please,
Thanks,
AV8TOR