). I've had a race crank professionaly balanced.. Its mega involved and not just about weighing rods and pistons etc.I used Vibration Free who are an outfit more used to balancing everything up to F1. It wasnt cheap!
They required the whole motor. Diagrams how it was mounted, at what static and compressed angle. I had to supply everything and the motor assembled with its flywheel. The motor is then spun up to its max working rpm and the imbalance measured. It was very hard to do (i was told) as the vespa rotary crank isnt great and due to its valve cutaway introduces more issues. Anyway Steve the guy there sorted it to a degree. The problem was that due to the reduced crank webs there wasnt much metal to add the weights. The result was a much improved motor and my frame didnt crack anymore. I only raced that motor once as circumstances changed and I went with Charlie who produced my current Falc based motor. Look in scootering for images of the Falc crank and all the attention to balance. This motor is a hundred times more smoother than my old one, even with uprated mounts.
