Pulled down the top end on the MSS tonight due to a heavy vibration that developed suddenly about 1000 miles back. On the whole, the engine was running good and strong right up to being pulled apart. The vibe began at about 70mph and over the period of a couple hundred miles dropped down into the lower speeds. In the end it would vibrate your feet off the pegs at 45mph. More interestingly, the vibration was most pronounced with moderately light throttle openings. No real noticeable vibrations at wide open throttle. In the pictures, you can see light seizure to the piston skirt both front and rear. Prior to the pull down valve clearance came out to 0.006 in for the intake and 0.007 in for the exhaust. Lucas mag was set to 36 degrees BTDC with an auto advance unit in place. Carb is a Amal monoblock with stock jetting.
In the video, you can see the connecting rod has a binding spot. ( Ed G. pulled the bottom end apart shortly after this page was written. It turned out to be a failed big end. The race had cracked it several places. Since then the old Velo is back up and running. I have yet to change out the piston and barrel)
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