The flywheel type looks similar to the Villiers ones with a cam on the flywheel boss. Villiers engines don’t have a key but rely on the taper to keep them in the correct position. Basically, if you put the flywheel onto the crankshaft and tighten it up on the taper it will produce a spark when you spin it; the knack is to put the flywheel in the right place so that the spark occurs at TDC or just before (BTDC).
To achieve this it is best to remove the cylinder head, then rotate the engine in the direction that it runs. For an engine of this size you should stop the rotation when the piston is 1/4″ from the top of the bore before it reaches TDC. Do not turn the crankshaft, and if you can lock it in position so that it doesn’t turn even better.
Next you will fit the flywheel loosely on the crankshaft, fitting the flywheel nut to prevent it falling off. Do not tighten it to the crankshaft yet. The flywheel can then be rotated around the crankshaft and the points gap observed. Rotate the flywheel in the direction that the engine runs, watch the points close, keep rotating the flywheel slowly until the points gap starts to open. This is when the spark will occur. Without moving the relative positions of the crankshaft and flywheel you should now tighten the flywheel nut to lock the tapers together.
The engine should now be timed.
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