Does anyone know how to adjust the rpm at idle on these motors? I see a screw inbetween the IP and the engine block but it is frozen in place...

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Screw inside 14mm collar nut? You must loosen the collar and turn the screw simultaneous. Best method is 14mm deep socket held with vice-grips and screwdriver through where ratchet usually attaches. Best to make this adjustment with engine idling.

Be very careful with the nut on that screw. If you force it, you can fracture the ear on the IP with catastrophic results (a new IP).