I recently went to New York City to see Iannucci's Honda-6, and to talk to Nobby Clark, the man who was tuner for Gary Hocking, Mike Hailwood, Jim Redman, and on and on up to Eddie Lawson. To have both in the same room was a considerable constellation of history.
The main bearings on the 13-inch long crank are caged roller, and the cages each have half-chevron-shaped grooves milled in their ODs, to pump oil out of the bearings. I was told that this made a significant, measurable difference in power. I was always sure that friction must have eaten a lot of the six's power, but I never had any details like this.