Ride #3 ended in more top end damage.
I took it out for about 10 miles and planned on tuning the carburetor. Again, toward the end of the ride when the engine was warm I noticed more top end noise. Then when adjusting the carb, things went wonky again and I shut it down. This afternoon I took the valve cover off to find two more bent intake pushrods and another broken L Intake Rocker.
I called the mechanic who rebuilt the head. He thinks the problem is coil binding. He had the cam when he set up the valve springs. He said it is not the stock BSA cam, but one of the sport cams. He said at maximum lift there should be about a 0.030 gap between the spring coils. I couldn't fit a 0.030 feeler between any of the intake or exhaust spring coils at maximum lift. Sooooo.
The plan is to order new push rods and rocker. Assemble the top end, and DO NOT attempt to start. He wants me to bring the bike to him so that he can check the springs at maximum lift to determine the best correction. He mentioned removing shims on the valve springs, deepening the spring pockets in the head to allow for proper spring pressure, or shortening the push rods.
I'm pretty bummed. I feel like this is one of those things an experienced mechanic would have checked and avoided breaking things.
The first time this happened I thought it was builder error. I thought I had set the push rod on the edge of the cam follower instead of seating it on the follower.
This time I was careful to make sure the pushrod was properly seating on the cam follower. But I didn't know to check valve travel for for coil binding. It made perfect sense when he explained it.
If I ever rebuild an engine again, I will know to check such things.
Sigh.... dang so close.