Alan, in your emphasis of the apparent across the board loss of compression lies a probably important diagnostic issue. IIRC, it was dcarver's '06 that had a dramatic compression loss in one cylinder due to a chunk of carbon interfering with the seating of one valve (intake IIRC). Seems to me that it occurred in Death Valley and the bike was seriously short on power until he got the problem diagnosed and fixed a week or so later. So, I gotta agree with you -- makes sense that carbon interfering between valve and seat is highly unlikely to yield an across the board loss of compression, especially a loss of roughly the same values in each cylinder.
So, could Nightshine's bike have suffered a carbon caused ring problem at the same time that he had other valve guide issues? Or is it something else that might be related to exhaust valve guide erosion?
I'd be interested in your thoughts on valve piston interference with the cam shaft off by one tooth. Isn't that what happened with the cam chain jumping the sprocket on your or Howie's or Patriot's bike? (Seems that at least one was from putting it together on the wrong marks, but the CCT caused crashes jumped how far?) Or was it further mistimed than one tooth to cause the valve crashes?
I don't doubt that some of Ivans's observations were valid concerns. Unless I hear a better explanation of what MIGHT have occurred to cause the excessive leakdown though, I still think there's a couple problems with his conclusion that the shop crashed the valves and used a ticker fix ruse as a cover for rebuilding the top end after that damage. But you've been through a valve crash with this engine, what say you on that?
EDIT to add: It's worth rereading the first three posts by Nightshine (the OP) and Zac's post.
Nightshine specifically says that he had observed no performance degradation between this service (December) and the last one (March) which he implies was the only other time he'd made the trek to R.Y. for service. He also does not say that it was Roseville Yamaha that did his first (of two) valve lash checks and it appears that, due to mileage intervals, it was NOT R.Y. who did the first valve lash check scheduled fro 24 K. (This would remove the possibility of R.Y. having mistimed the camshafts before the bike was brought in this December).
Nightshine also says that the valves were not seating properly in part due to the valve guide wear, and in his second post relates that carbon deposits were interfering with the valve seating AND rings.
Zac then clarifies that in his own bike (O'vale's) and in Nightshine's, the "ovaled" wear of the exhaust valve guides contributed to carbon build-up between the valves and seats that had the valves improperly seating.
Noting this last part, and the issue of coincident carbon/piston ring sticking problems, might go some ways to addressing why excessive leakdown was observed in each cylinder.
