Little update with this setup regarding the full circle crank:
Since the rebuild this bike was ridden maybe ~200 miles. The cheapo silent blocks from treats wore out fairly quickly. This weekend I swapped out the thrashed blocks for some of the nice $14 ones as well as the counter spring with a 30# McMaster gas strut.
The new blocks are much harder than the cheapos and the vibrations are considerable. I had to cut some weather stripping to fit behind the headlight bezel just so it would rattle apart at idle.
The problem I’m having now is even with the carb clamped down, at ~6K it will rotate back and forth and at around ~7K fuel foams and spurts out of the top around black piece.
I’m going to swap out a bottom end with a stock crank and see if the vibrations become manageable