I have been running with the piston oil holes blocked for the last two years. I don't think they are any benefit and besides that it is better to have that oil going to the cams. A few other people agree about this but there are lots of other people who prefer to run the oil holes. (some people even like two or three holes!) I doubt there is a modern engine that has oil holes in the liners. When you have modern pistons in a Vincent then it is running more like a modern engine. I wonder what would happen if you were running some of those liners with the holes to high but no oil coming out of them. I think it would work OK. My engine has negligible oil consumption, just like a modern engine. My engine can run wide open up hill at 4000 RPM 85 MPH two up for half an hour or more without problems. I don't think the pistons need more oil than they get from the crank. Really all the oil that is circulated in the engine gets chucked around everywhere by the flywheels before it is pumped out anyway. Pumping the oil to the cams first probably doesn't reduce the oil to the piston skirts much at all.