Both the rotor and eccentric journal. If you set the cut down e shaft
and rotor with the balance weights  on two horizontal knife edges and
it does not rotated  that should be sufficient static balance.

Static balance is not enough. The engine must be dynamically balanced. You can theoretically achieve static balance with a single counterweight, but the dynamic imbalance would be extreme. Yamamoto has a mathematical derivation of the requirements for engine balancing for any number of rotors. In practice, it is a little complicated to properly balance the engine. At Deere, we would weigh the rotor, find its CG, make a bobweight to the same mass, spin balance the bobweight, and then find its CG. We'd then clamp the bobweight on the eccentric so the bobweight CG position was coincident with the rotor CG position when assembled (a location that itself requires a bunch of measurements), put on the counterweights (with extra mass), and send the whole assembly to a balancing shop for dynamic balancing.

Jon Lauter
Rotary Power Marine Corporation
www.rotarypowermarine.com

All true and that is why I said >static< balance.
I was sure I sent that balance diagram along with the message Jon. Did you
not notice? :-) Here it is again.

To Don Dunbar:
This gave me an idea Don. 

How about a 13B turbo two rotor rotary powered boat made in Perth?

Paul Lamar
 
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