Been wanting to do this for a while now. An auto-electrician who should have known better tested my old Simpson-Pope coil (Wico/Wipac) and suggested I get a new one, because it was giving a low Kohm reading on test and he thought the spark might be too weak. He thought it should be around 8 Kohms. So I purchase a brand new one at great expense and guess what? It tested exactly the same as my old coil. I put the old coil back and the engine has good spark. So the new coil will act as a spare.
Different makes and models of lawnmower engine will give different readings on test. Older engines from 1950s back in time will generally test lower than modern coils. I have started a list and hope others can test different coils and we can make up a list. This is for a basic coil test using a multimeter set to 20 Kohms, through the spark lead (black terminal) and positive ignition wire (red terminal). It would be good to know the "as new" ranges and "working" ranges to determine how low or high a reading can be before ignition problems occur.
New or good coil test:
Simpson-Pope 2 stroke Wico\Wipac coil (c. 1959) - 4.24 to 4.25 Kohms
Early Victa 2 stroke e.g. Victa 18 coil (internal flywheel), up to Mayfair etc. (1960s) - generally 6-7 (to 8) Kohms range is okay. I've still got good spark from a coil testing as low as 6.
Later Victa 2 stroke (external to flywheel) - new, around 8 to 8.24 Kohms
Briggs & Stratton - generally 2.5-5 Kohms
Does anyone have information on 2 stroke Villiers coils?
