What was found
REMOVED CARBURETOR, WAS UNABLE TO PROPERLY LEAN. NO RISE AT ANY RPM. ROUGH AND STUMBLED WHEN REDUCING POWER AND WHEN ADVANCING POWER. HAD CARBURETOR O/H RS NR V1RR580Y. INSTALLED AFTER O/H AND WAS STILL UNABLE TO LEAN AT ANY RPM WITH IDLE MIXTURE SCREW 4 TURNS OUT. STILL ROUGH AND STUMBLED. THIS WAS THE (7TH) CARBURETOR SUPPLIED, THAT FAILED TO WORK PROPERLY. REPLACED WITH A O/H CARBURETOR AND WAS ABLE TO LEAN 25 TO 50 RPM AT ANY THROTTLE SETTTING. WORKED GREAT AND TEST FLIGHT FOUND ABOUT 20 KNOT INCREASE. LIKE A NEW PLANE