I have never retained a flywheel. I will for initial testing on this one. It is a Craftsman 29cc 4-stroke. I know it is a wimpy engine. Someone else used this engine in a 1/4 BUSA fokker d-7 and was real happy. I am building that exact plane. The idea of it sounding cool appeals to me. I am interested in running it with the minimal time imput, at first.

From the pics you can see I have it stripped down. The front of the flywheel is flat. If I make a bushing with a knurl to hold the prop it will spin against the prop hub. What is the most expedicious way to prevent that. I am thinking one of those nasty looking lock washers with a dozen or so radial teeth.

If if gives reasonable power I will probably set it up with electronic ignition and carve off all the un-needed bits like the other one. It was my "practice" case. Unfortunately the jug is ruined from water inside. I did not nottice that soon enough. Swapping the case is probably not an option. The bearings and seals are super tight and difficult to remove and install. I think they must have used an arbor press with depth stops.