The Sandcast 750's
Sandcast Bikes
Unable to gauge demand for the new bike accurately, Honda limited its initial investment in the production dies for the CB750 by using a technique called permanent mold casting (often erroneously referred to as sandcasting) rather than diecasting for the engines. Once the demand for the bike became clear, Honda switched over to die casting using production dies for the engine cases. Due to their rarity, the sandcast bikes have been particularly desirable.
The information in this article comes from postings to the SOHC/4 Forums, many from member, Ted Nomura.
The earliest CB750′s had gravity cast engine cases erroneously referred to as sandcast. The early engine cases, which were made prior to the completion of production casting dies, were actually cast using what is correctly called permanent mold casting which uses metal casting molds not sand. It is the gravity casting method and the molds that results in a rough finish to the part. The later engine cases were cast using a technique called die-casting where the metal was pressure fed into a casting die resulting in a smoother surface finish, better quality control, and a generally stronger part.
There are several distinctive characateristics of this series of engines:
- The engine cases have a distinctive rough finish that resembles the roughness of 400-600 grit sandpaper.
- The engine serial number is CB750E-1007414 or lower.
- The clutch cover is held on with 10 screws – the diecast engines have 11.
The sandcast engines were fitted only to the earliest 1969 models. The first thousand bikes were hand built, mostly in California, as Honda tested the market for this new model. Most of these bikes would have been registered prior to August 1969.
Use caution when buying anything designated as ‘sandcast’ since this is a label often incorrectly tacked on parts and bikes by questionable sellers seeking to drive up prices.
The Honda CB750 Sandcast Only Owners Club is a great resource to learn more about the sandcast CB750.