Valve timing
My current Manx Norton, my previous Honda K4 racer, my Rudge Ulster, my Vincent, all have equal lift between 5 (the median value) and 0 btdc. Only one of these was set that way by me. The Honda (works camshaft) came that way.
I asked the guy who takes care of my 86 bore Manx Norton (145 mph at Chimay last year), and who also builds all of Andy Molnar's 92 bore Manx engines (£27,000 a pop), if this was just coincidence. Nope. Any engine timed for equal lift within a few degrees of TDC will fly. Ignition timing is far more critical, and has to be right. (The Manx is 13.8:1...)
When I timed the Rudge, with a presumed hot cam for which I had no timing figures, I didn't bother with opening and closing figures, but set it for equal lift at TDC. I got about 3 degrees btdc. Before being detuned (down from maybe 7.3 to 7) it would touch 100 mph, now barely does 90. But cruises easily at 80. One swallow does not a summer make, but I think it indicative.
(As a sidenote, my experience is that the combination of a "race" cam with a low compression piston results in a motor that will go up the side of a house at zero rpm, not at all "buzzy".)
Even if you choose not to time your motor that way 1) it's a useful check to make sure you aren't a mile out and 2) if you should ever (heaven forfend) have to time a bike by the roadside, you now have an easy way to do it.