Small Engines (Lawn Mowers, etc.): Villiers 4 stroke motor, driving shaft, stroke motor

Question
Hi John,
I hope you can help me.
I have an old gear train driven concrete mixer (brand unknown) powered by an old villiers 4 stroke motor. The motor is very similar to a Villiers C10 that I have but the main differences are a/ the C10 does not have a reduction gear box. and b/ the one I want to fix has gaps in the flywheel to clean and adjust the points. The flywheel is not keyed but has a self pulling nut, which means that the timing cam can be anywhere in 360 degrees - sheesh.
I can work out when the spark is firing at TDC but do not know how far before TDC I should set it!
The second problem is when it was together, it would consistently fire 10 to 12 shots as if it was going to start but it never would. I have cleaned fuel lines, changed fuel, changed carby - still the same 10 or 12 shots and stop! - any ideas? The only other thought I have had, is if the gear train is jamming somewhere - causing it to stall.
Hope you can help - thanks in advance Ian. P.s. I am 60 and have had a lifetime of experience with all sorts of stuff.

Answer
Hello Ian:

The Magneto is Timed so that the Contact Breaker Points Commence to Open when the Piston is 3/16" Before Top Dead Center. A Rough Check on the Position May be made Without Removing the Cylinder Head, by Observing the Position of the Keyway on the Driving Shaft when the Points are Just Opening; The Keyway should then be 27deg before top. Accurate Timing can Only Be Done with the Piston Visible. If the Timing is Off Enough the Engine will Operate as you Described. Get the Timing Set Correctly First, then Let's See What Happens. If you Hit a Snag or this Does Not Correct the Problem,  I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. Have a Happy Holiday Season and May the All Mighty Bless You and Yours. Be Safe and Happy. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Thanks.

Respectfully

John