fontyyy wrote:

Chester362 wrote:
As for lubrication, when running, the primary compression should be forcing mixture through the bearing.

If that's the case then why do the other 2 bearings have lubrication from the top cylinder transfers? Even on the RS when it's got to cost power to mess the base of the transfers up and cost money to machine the oil ways. Matt suggsted long ago if power was all you were after you should fill them in.

And why did the mc28 add a drip feed from the oil pump to that bearing?

Obviously the oilways are there to aid longevity of the bearings. If they weren't there, the engine would still work.
Maybe the loss of power due to turbulence is offset by the reduced drag of better lubrication and better reliability?
Yeah, the late MC21 and '28 engines have the oil pump feed down the crankcase bolt hole. Good idea on a road bike. I would think it means that the right side bearing is under more load and benefits from the additional feed, rather than an inherent design fault.
Sticking to maintenance schedules would ensure failures are non-existant or due to other reasons, eg, poor maintenance or unusual failures of components, etc.....