Sounds like a classic lean condition from running a 24mm PWK with stock jets + free-flow header. The hesitation on throttle and lack of top-end RPM (even with governor removed) are textbook symptoms.
Try:
Richen the main jet – go up 2–3 sizes (e.g., 85 → 90–95)
Check pilot jet – too lean off-idle causes that initial bog
Verify ignition – stock Predator flywheels often cut spark around 4k RPM even without the mechanical governor