...That little setup got on the pipe as soon as you got past half throttle. When it got on the pipe, you had to go close to WOT to keep it fr
This is quite understandable.
When the engine get 'on the pipe', its RPM and inflow of air increase significantly, even at the same throttle setting.
I envision the YS carburettor, with its variable orifice size mid-range fuel control...
Increasing the intake air-flow through any engine's carburettor venturi, will not increase the fuel flow by the same amount.
With YS, and its 'non air-flow dependent' duel delivery, the engine will get roughly the same amount of fuel (no increase in fuel flow), for a significantly higher inflow of air and thus fuel requirement...
This is no surprise!
You guys are exactly right as to fuel flow characteristics on the YS metering system. I tuned the system for 16K with a broad band pipe and got my speed from pitch. We used a flying start, y'see, so you acclerated by diving for the starting line. The trick with high pitch was to not stall it. Different strokes......