Info that might be useful to members, ring set 13011-MV4-305 available in USA for $16-00 from powersportsplus.com and $22-00 from mrcycles.com. Postage for powersportsplus appears to be around $25-00 to most destinations, Uk, Oz. Worth a look.

I take it the rings NC30,and CB400F are the same part numbers,
Because they list nothing for NC30.

From the info on this site and part sources in UK, P/N 130011-MV4-305 is the new P/N for the NC30 P/N 13011-MR8-000. It could also be suitable for the CB400F, Honda just rationalizing their parts listings.

Honda parts sources in USA are like those in Oz, they never list NC stuff as the bikes were not an official import from Japan.

Powersportplus in USA also lists head gasket 12251-MR8-601 at $24-00 US each.