I had a vibration problem with the Jaguar on the Playboy. So I made up a mock up and had a machinest make one out of aluminium. Solved my vibration problem and picked up a few more RPM. Should have tried the unballanced prop trick first as I did with my Drone diesels. See photo. Painted a prop blade with epoxy paint to aid the counter ballance of the crank. Workes great. Jack