OK, well like Frank says, perhaps if that top sheath is removed, the conventional recoil will fit. Try removing it and taking more pictures. I would attempt to resurrect that carburetor, I’m sure you can find an oring to fit the bowl. I’m guessing there is a fixed high speed jet somewhere in the bowl/nozzle, that will have to be cleaned out also. I’m guessing the ignition will need to be serviced/overhauled. And, you should probably replace the water pump impeller, and change the gear lube.
An interesting project for sure.
Take pics of inside the carb with the bowl off, hopefully we can direct you to the fixed high speed jet.
And yes, rotating that throttle handle does indeed advance the ignition timing, unlike fixed timing used on many of the four stroke lawnmower engines. The ignition cam and carb throttle linkage must be syncronized to work properly, but I’m betting it is close enough the way it is to work fine. Not quite sure how it should be set up with that crazy carburetor anyway, so don’t mess with it.
