850 Ultra XP lean bogs when secondaries open

On the traditional 850’s(1.56 x 1.75), I often end up with quite large squirters...... like 40-47.
Anything over a 35, and the hollow screw should be used.
With downleg boosters they’ll usually need the 50cc pump on the rear.

I believe the XP850 is a 1.56 x 1.69 carb. I’m not really a fan of that configuration. It’s like the old “830” .
Less of a pronounced Venturi.
I prefer the smaller Venturi and larger throttle bore arrangement(HP950).