The Sandcast CB750
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. A good resource for owners of these highly collectible early CB750′s is the Honda CB750 Sandcast Only Owners Club. You’ll find lots of good information there including details on changes to the bikes in the early years and photos and analysis of the early production bikes.
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.