Makes perfect sense to me.Fun fact: Harley tuners drill CV40 vacuum ports to 1/8" diameter, versus the 7/64" favored by KLR tuners on CVK40s..
1 carb feeding TWO 600cc cylinders would probably have a stronger more consistent intake vacuum, even near Idle rpms, than a single cylinder 650. So the vacuum slide could be allowed to 'lift' quicker. They are about the same in suggested Maximum operating RPM, I think.
ps, But I 'think' I might beat most XL1200 Sportster riders across an intersection with my KLR650.