After much messing about i've found the ring gaps are way too big.  I should have taken the rings off and measured them last time, but for some reason I got it in my head that i wouldnt get them off without damaging the, even though i'd  managed this hundreds of times on my MZ (i'm blaming someone else for talking me out of it).

I have new rings but the lower ring gap out of the packet seems slightly large, while the top rings will need grinding.  Also my bore guages seem worn out/broken as I can't get a consistent reading from the 2-3" one.  I'm going to buy a internal micrometer so I can be sure of the piston/bore clearance before i go any further.

Still no wiser as to how it wore the rings out in less than 150 miles, my hope is that I don't have some other issue and I somehow gapped them incorrectly first time round