Sorry to hear that Phil. Looks like its barrels off & a new top end rebuild kit from Gavin at Jap4. If its seized, it sounds like it has, you may need to hone out the barrel as well. Probably some more experienced guys on the forum can give you more detailed / better advice.

When I get back from my travels, I'll be being doing the same inspection through the exhaust port when I clean the RC Valves. I've no idea what I'll find yet!

Good luck.
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Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30