I just ordered some parts directly from Yamiya, which I had brought over from Japan via someones suitcase !
I put the prices onto a spreadsheet and compared with UK suppliers etc.
There are some amazing price differences (even adding UK VAT and import duty costs) particularly on Genuine Honda fasteners/bearings/chains etc
One example is Yamiya '14- HONDA CB750 NUT, 8mm CYLINDER HEAD' ... Over 600% difference in price between Yamiya and David Silver in the UK ( Yamiya parts are individually plastic bagged Genuine Honda parts)
The following is not strictly sandcast / K0 related, so please remove if you consider it inappropriate Steve
I just noticed that my original 03/ 1971 CB500K0 seat foam has 'Bridgestone 164B02 or is it 164802' printed on it in blue ink plus 323 922A embossed into it. So I guess BS must have been an OEM supplier of the foams to Honda. I wonder if they supplied the red foam material too?
Also noticed on my CB750K0 wiring loom that each coloured wire has 'Sumitomo 1969' printed on them in tiny text.
Other Honda Suppliers OEM's I know of are as follows . Can anyone add to the list?
Hitachi & Nippon Denso for alternators/regulators/Solenoid switches/flasher relays
Riken for piston rings.
ART …. Pistons,
Yuasa for batteries,
Nippon Denso/Nippon Seiki/Fuji .....for clocks.
D.I.D. ..... Chains /wheel rims
Sankei ..Exhaust Systems,
Daido Metal ....Crankshaft Shell bearings,
Bridgestone/Nitto/Japanese Dunlop......Tyres,
Tokiko .....Hydraulic brake parts,
Stanley Electric .... Lighting,
ASK .... Brake linings.
Neiman ... Euro model locks.
Nippon Oil & Fats... CandyTone paint,
KeiHin ...carbs,
NGK/ ND Spark plugs
Showa ...suspension components.
Mitsubishi ... ..CB750 sandcast / K0 Valves (CB500 too)
ARAI/ N.O.K.... oil seals
NTN & Nachi & Koyo... bearings
Mitsuba..... Horn & Starter Motors
Oil Filter element .... Tokyo Roki
Takasago ... Sandcast/K0 primary chains
Tec/ Toyo .... Sandcast/K0 Bar switches / Ignition Switches
Toyosha .. Sandcast /early K0 'Antimon' alloy tank filler cap.
Yamada ... CB500/4 oil pump
Uehara ... CB500 Alternator cover plate
Signal-stat... USA flasher relays
Asahai ... Disc brake pads