bikemike
loud pipes save lives
Only strato i have does run all fuel oil mix to bottom end and through the transfer port to top end the top butterfly is air only and it goes straight to top end only. That is the only strato i have worked withI think this is a simple and short important piece of information that goes to answering the question in the title. There is a chance some design or designs that make it to market the clean air gets around bearings instead of the mixed air.
Some place near your strato transfer ports, the ones that pass air only it would stand to reason there is less lubrication. The guys that take these things apart probably can tell if it is an issue.