Engine was hard to start, outside temp around 50 F. Normal pre-flight checks, R/L ignition checks were good, 75 rpm drop each side. Full power check after engine warmed up, no defects noted. 12 gallons fuel on board and feeding to carburetors. Engine stopped just after liftoff at full power. Engine had just undergone a 100 hr inspection 3 hours before sudden stoppage. Only items changed were L/R carburetor bowl gaskets replaced with new. Ground run up after inspection and replacement of 2 carburetor bowl gaskets was normal, no defects noted.
