A10 Kickstart shaft outer casing bush

[trevinoz]

There was probably a good reason BSA used steel for these bushes.
I think that bronze would wear quickly with the downward force.

[BagONails]

There was probably a good reason BSA used steel for these bushes.
I think that bronze would wear quickly with the downward force.

aha but mine starts first kick every time so would never wear out 

[limeyrob]

Thinking back to both BSAs and other marques I think steel bushes are used whee there is exposure to grit and intermittent and partial movement - kick starts, gear levers, brake pedals.  Steel does a good job in these applications so long as its oiled. Bronze bushes are nice so long as thee is a seal or they are in a clean environment.
This has reminded me of a 1960 VW Beetle we had for many years. All the front suspension bushes were steel on steel with grease nipples and no seals.  They lasted years and years so long as they were kept greased.  Later designs replaced them with sealed ball joints which didn't last as long but could be neglected.