Danno,
Thanks for the reply. I'm pretty sure the compression numbers are accurate. The spark plug end of the hose also has a check valve on it. After a few rotations it maxes out. The cylinder doesn't have to recompress the hose volume on each stroke. (see pics). My head gasket and all the other associated new gaskets and stem seals will arrive tomorrow. I've got my valve spring compressor waiting in the wings. We're gonna tear the head off tomorrow, after we do a quick wet compression test.
I'm hoping for a blown head gasket, and not burnt or bent valves. if it is the head gasket, I'll replace the stem seals for good measure, then lap the head and put it back on. If it turns out to be the pistons, then I may opt for new ones with a slightly higher compression ratio (maybe like 10 or 10.5) My BMW R1200 RT is like 12, but it requires premium unleaded.
Wish me luck and thanks again!!!
