Since this is a conversion forum...here goes a Idea! The big engines that are hard to flip fast enough to hand start...why not tap another place in the head for a GLOW Plug! Then prime with a little sqirt of glow fuel through carb opening. Attach glow battery and back bounce start it. The engine should REV up good enough for the regular spark ignition(flywheel type or CD type) to keep engine going. Sould work good if done right! Capt,n