Mystery motor from an unknown vehicle

I got a message from a fellow hobbyist that he had found a Cox car engine from a pile of his dad's old hobby stuff. Of course I was interested, as it was something new to me, I had never even seen one of those before except in pictures.

Finding info about these was also a bit difficult so I thought I'll share this experience. Special Thanks to Lieven "Overlord" for advice

As usual, this one was also stuck with castor gunk, nothing moved. Here it is "as delivered":



You can barely see that Babe Bee lurking underneath all that stuff I couldn't find my non-metric Allen set so I had to wait until the next day so that I could stop by at the parts store to pick up another set. These new ones are "Made in USA", I try to buy quality stuff when I can. Besides, these are "gorilla proof"

So, after I got home I got the brass "bell" off first, revealing the centrifugal clutch:



With some "gentle" persuasion, the trumpet-shaped flywheel-clutch combo came off. It is only held on by the taper on the crankshaft and its mating surface on the flywheel. There are two small discs that rest in the wedge-shaped recesses of the starter rotor, the purpose of this arrangement is to work as a one-direction clutch that engages the pull start system to the flywheel when the starter cable is pulled, and releases it when the engine starts. The little discs were sticky with castor residue, resulting in a stuck clutch:



The next step is to remove a circlip, after which you can pull the starter rotor, and the cable return spring becomes visible. I suppose if it were any cleaner, it would have attacked me right after I pulled the rotor, but this one was sticky as syrup, just like everything else on this engine.



I managed to pull the entire starter cable-spring assembly, and what remains looks more familiar, note the circlip groove on the neck:



Here are the car engine crankshaft and a standard one side by side. The car engine one is a lot sturdier, probably because it will tolerate bigger loads but also it will allow a taper style attachment of the flywheel, probably to prevent cranks snapping under sudden load application. This one didn't turn smoothly, it had probably overheated at some point, which is not surprising as the engine is in a rather confined space in a vehicle and also the starter cable assy being plastic prevents cooling rather effectively. A light polish with some polishing paste took care of that.



Then after a warm ethanol bath in the ultrasonic all the parts got my usual polishing treatment. Except the plastic parts of course. They went to a warm hand dish detergent bath. I used an old tootbrush to polish the heat sink, glowhead and backplate, as they have a lot of recesses. After the polish another ultrasonic bath to get rid of polish residues and then re-assembly. Before and during the assembly I applied light oil on all the parts.

I didn't get any pics of the re-assembly phases as my hands were oily. Getting that clean-as-a-whistle but slippery as... well a very slippery thing spring back in its place was a #%^+¥! but I finally did manage to get it there. The starter works as a charm now that both the cable and the spring are clean. Here is the finished product:





It's an interesting piece of engineering for sure but I think I still prefer aero engines

Oh and I still am not sure what vehicle this is from. Roddie suggested Chopper earlier, this one looks a lot like it but the clutch is a little different. This one could of course be a mix of parts too. It has only one bypass port so it's no hot rod, I am still guessing it is from one of those "entry level" toys. The red part on the adjustment lever had a hole in it so it probably has been adapted for R/C use at some point.