I've found that anytime you get below 3500 RPM, you can get into a engine lurch situation.
Usually a combination of two large pistons, two very large throttle bodies, drive line slop, and sensitive fuel injection, and much lighter flywheels than a Harley.
I've got 15/41 and I find it hard to even do 35 MPH in 1st gear without the bike acting up. At 4000 RPM, no problem.
The fact that it runs relatively well at all with dual 62mm throttle bodies at low RPM is a wonder of modern fuel injection.
Try this with dual 62mm carbs at 3000-3500 RPM and it will give you a whole new definition of the word driveability (not).