US Engines 41cc 2.5 cu in engine.

 U.S. Engines gasoline power plants readily deliver the advantages that brought you to giant scale flying in the first place. They boost your model's scale looks and sound. You save on fuel costs by using regular unleaded gasoline and 2-cycle oil. Includes a special throttle linkage which makes it ready for rc use. Its very easy to operate. The solid state ignition has no points which makes it maintenance-free. Two bolts hold the coil on. Has a smooth factory balanced flywheel, chrome plated cylinder bore, and full roller bearings. Propeller and spinner-ready.       

  GREAT ENGINE FOR THE Great Planes' Pitts Speacial ARF! And many other Large And Giant scales.