I see that the B31 cylinder head to cylinder does not have a gasket. Is it wise to put a thin skim of sealant on assembly or does it seal successfully dry?
It is a spigotted joint and should seal dry without any sealant. It may be useful to lap them together with a little fine grinding paste but this is best down with the head and barrel off the bike to ensure that all of the grinding paste can be thoroughly washed off. You don't want any of that ending up in the engine. If it wasn't leaking previously it will almost certainly be OK.
Ok. Thanks.