by Skywatcher » Sat Sep 21, 2019 7:23 pm
Hi Az
Sounds like an older engine if it has breaker points. First this I would do is to isolate the ignition and run resistance checks on the primary an secondary circuits. Sparkplug lead to laminations should be in the 3,000 to 7,000 ohm range, that's the secondary circuit. The thin wire that goes to the breaker points to the laminations should be in the 0.5 to 3.0 ohm range.
Next, check the breaker point gap, Haynes manual says 0.014". Take a 0.012" feeler gauge and a 0.016" gauge, if the .012" fits and the .016 does not, you're probably close enough. Isolate the points from the coil and the condenser, use your ohm meter between the moving point and the engine frame to see that the points are actually making and breaking contact.
Check the flywheel to ignition coil air gap, Haynes manual says 0.012" to 0.020". Also, check to make sure the flywheel key is not partially or fully sheared. Finally, check the condenser. Touch the condenser across a 12 volt battery for ½ a second and remove. Take your multimeter set on volts DC and measure the stored voltage in the condenser. You should see about 6 volts to start and the voltage gradually drop as the condenser discharges through your volt meter.
If everything checks out, you should be able to reassemble the ignition system and have spark. If the coil or condenser do not check out, replace. If the points do not check out, clean or replace. Hope this points you in the right direction. All the best,
Sky
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