rhythmic vibration

The balance of the motor would be thrown off if someone put the counterweight on the balancer.........We took in a 340 Cuda that had the same issue......motor was just built by a Pro Shop, and they installed (or an inexperienced worker IN the shop) the counterweight in the back of the balancer..........That looks like a stock unit on the motor........If you have a counterweight behind it, it's a culprit...........:read2: