I've always just removed the side cap and stretched the outer spring put it back together and if it revs out too fast on idle put a brass washer behind the cam and set the poppet on C , then I just control the RPM by the throttle control.
But correct Procedure is.
Governor Spring & Calibration Spring Specification: The standard outer governor spring for a G4'LM carburetor is typically the red spring (Part No. CRO3417A), rated at approximately 150g tension. If an incorrect or stretched spring is installed, it changes the vacuum balance against the diaphragm.
Field Workarounds: While stretching the spring or inserting a brass washer behind the cam can force higher revs or adjust idle, doing so bypasses the engineered vacuum governing range, which can lead to unstable governing or over-speeding under load.
Poppet Valve & Restrictor Confirmation Poppet Valve Setting ("A" vs. "C"): Factory specifications for 4-blade disc models indeed require the poppet valve set to "A". This restricts maximum airflow/vacuum response compared to setting "C", intentionally running the engine at a lower, safer maximum RPM to account for the heavier mass and momentum of the 4-blade cutting disc.
Vacuum Hose Restrictor: Yes, the vacuum line or end-cap fitting for 4-blade disc variants features a built-in restrictor (or a restricted nipple hole) to dampen the vacuum pulse. This prevents the governor from reacting too aggressively to rapid pressure fluctuations.
