[DrVirz]

You are spot on, at 900 rpm It is incredibly rough, the worst of the whole rev range.

It tested at 125psi as I couldn't get the fitting of my compression tester down to the spark plug seat (fitting too wide). So it had to sit up the spark bore, at the point where the bore tapers in, same point the coils taper in. There's a good chunk of volume there and therefore compression is reading low, however in reality it would be higher. I will cut some threads on some bar stock so I can get it right down to the plug seat.

Ista states that 10 - 16 bar is working range.

FYI it has brand new rings and block has been honed (lapped) with AN30.