You can always go back to basics with any engine. So long as you can see the points opening and closing, you know the direction of rotation and you know when the piston is at TDC you should be able to time it up.
I’m guessing that this engine has the cam on the flywheel.
Firstly you want to loosen the flywheel, then set the crankshaft so that the piston is at TDC. Then turn the flywheel in it’s normal direction of rotation, wait for the points to close then keep turning the flywheel slowly until the points just start to open again- this is the point at which the spark is generated. If you can’t quite see when the points are opening I used to put a piece of cigarette paper between them, keeping a light pulling action on the paper whilst rotating the flywheel. As the paper is released then that is where they start to open.
As soon as you see/feel the points open, stop rotating the flywheel and tighten it onto the crankshaft trying to keep everything in position so that it doesn’t move.
This should work for any engine that has the camshaft inside the flywheel. I’ve used it countless times on Villiers engines.
You can add a little refinement if you feel confident as well. Really the spark should be generated just before TDC (ignition advanced) so you can turn the crankshaft slightly before tightening up the flywheel to give this advance; of course, if you do it too much it will fire too soon and kick back. This makes you swear and clutch your wrist!
On a small engine such as yours you should have no more than 1/4″ gap between the top of the piston and the top of it’s stroke to have an effective advance.
Best of luck!
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