As I start my Cafe Racer build based on a 1977 z650B1 I discovered that most of the wheel bearings are the same as a classic “Zed”, but the sprocket carrier is different. This led me to start recording minor details like wheel bearing part numbers so I didn’t have to research the same bearing information later.

The 1977 z650 B1 model has the following wheel bearings installed:

Note: 2016-04-22 – I have updated the front bearing info – it appears I had a 6302 part instead of 6203 listed so double check the bearings as you remove them from your wheel!


  • 6203-2RSH
  • 40mm x 12mm x 17mm


  • 6303 – 2RSH
  • 47mm x 14mm x 17mm


  • 6305-2RS
  • 62mm x 17mm x 25mm

Measurements are in order: (Outside Diameter)  x (Width) x (Inside Diameter)

Note: The z650-B1 Wheel Bearing located in the sprocket Carrier is NOT the same as the z1 carrier. The spokes are also different on the rear wheel as well as shoes and the hub size.

When replacing the bearings you do not need to replace them with the original style open caged bearings. The later style sealed bearings that come pre-lubricated from the factory and are superior in every way, they also have dust seals built into them.

Other Models

I will update this in due course but the rear disk models may have different bearings in the rear hub due to the casting differences mounting the disk.


Categories: Technical Data