im designing parts for a motorcycle which is a rotating horizontal valve near the exhaust port on a two stroke motor.
the valve weights about 150 grams and is coupled to another valve in a cylinder parallel to it.
a servo motor cycles it between about 0 and 90 deg at about 3 rad/s.
the bushings are supporting both ends of the valve which has a lenght of about 120mm and has a bearing surface of 10mm each side.
the valves(Reducing Valves) are made from high silicon casting aluminium 4xx series i believe.
im wondering if anyone has any suggestions as to whether sae 660 high leaded tin bronze or phosphor bronze would be best or how i could even calculate stress'es or wear on each type?

They are installed lubricated in two stroke oil and gets continuous lubrication from unburnt oil. btw the OEM bushings are a bronze graphite sintered type mix or atleast seem to be.

thanks for the link i shall have a look see if i can find some information.

Or  try DP4 material from GGB for example, from what I remember gives good performance under oil lubricated oscillating conditions.

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