I don't really know much about this, but just looking at it, a 40 millimeter carb has the ability, it seems to me, to pass a lot more air than a 40 millimeter valve.
Going to a bigger carb is, I think, going to mean slipping the clutch more. To get the real benefit you'll need to turn more rpm. At high rpm, obviously, the big carb has the ability to flow more than a small carb.
But then again, I could be totally wrong. If it was me, I would be dyno testing the two and see which one is better. Of equal importance would be, "where, in the RPM range, is it better", that is, if it is better? I would be comparing the area under the usable curve.
The damnedest thing is you have to spend all that money to buy the carb, and, do the testing.
Convert Area Metric <> Inch
MM To> Inch
40 mm 1.5748 inch
32 mm 1.2598 Sq Inch Diff. in Area
Diff. in Dia. 0.315 0.7013
Convert Inch to Metric
Inch To> MM
1.5748 Inch 40.00 mm
1.2598 inch 32.00 Sq mm Diff in Area
Diff. in Dia. 8.00 17.8130
Hi Al, Haven't heard from you in long time. Hope you are doing well and still turning 11,000.