How important are smooth bearings?
In my work selling model engine collections, I've encountered a number of engines that have a slight roughness in the bearings. This has been with various engines, and is not specific to a brand. Super Tigre, O.S., Ross, etc. Though I do my best to note this to buyers, I've had at least one engine returned.
I suspect the cause of the roughness, what you might call a "notching," is rust or possibly even congealed oil. Often it disappears when the engine is warm, returns cold.
Recently I've been evaluating an O.S. SF 46 with the standard R/C "SF" crank timing. It has a slight roughness in the bearings. Yet, it starts and runs great, based on test stand runs. Should I be concerned about the bearings or just run it?
thanks,
Peter