RE: Open or shielded bearings for a DA 85???
I believe that all roller, ball and needle bearings in an engine should be unsealed and unshielded. The only bearings that should be SEALED are those exposed to the elements. Take a look at an automobile automatic transmission or manual transmission. Caged bearings require minimal lubrication and are happy with the fuel/oil mix. The constant cycling of fresh and used lubricants in and out of caged bearing is a healthy thing. We are only inclined to run 20 - 25% lube in our fuel to accomodate plain bearings and the piston and ring.
Bill