If you take a plug wire end and place it 3/16 or so inch away from the mag case or tractor steel etc and turn it over so the impulse snaps and releases you should get a visible blue spark versus a thin wimpy yellow spark.

John T
 
I have spark...not strong but enough to start tractor. Just wanted to learn what reading I should get if I use volt meter
 
You can't read it with a volt meter! It's around 30-50,000 volts. Bigger problem than that is that it's an instantaneous pulse. It Can be read, even graphed, just not with any sort of standard volt meter.
 
I used to use my brother to check spark....had to see how far he jumped to tell how well the mag was working LOL.
I did have an apprentice that I stupidly lent my Multi meter to and he tried checking for spark on a lawnmower with it!!! Never said anything when he gave it back I found it to be junk the next time I wanted to use it, he didn't think he had to pay for it GRRRRR!
He was unable to use any of my tools again.
 
When I worked for a JD dealer a owner of a JD B came to pick up his tractor. It didn't start right away so the guy pulled a spark plug wire andheld it in his had while I cranked it over. He said it had some spark but not enough.
 
If the spark is weak, Id star with either cleaning/filing and re gap the points (or replace if badly burned or pitted) and maybe a new condenser if needed. After that the rotor may need magnetically recharged and the impulse spring may be weak. If the start spark is weak yet she starts and runs fine if pull started, I suspect a weak impulse spring. You cant get a reading of the HV spark with any Billy Bob Volt Meter.

John T
 
hayfarmer

Had and 80 yr. old farmer down the road, who used to do the same thing, stick his little finger in the wire end and point his finger at the block and say, not enough spark and then ask me if I wanted to check it out.. I politely told him no, I'll take your word for it..
 

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