# Briggs & Stratton magnetron coil test.



## flchevelleman (Feb 21, 2016)

Can I test a B&S twin 2 cyl coil in the block with a ohm meter?


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## jhngardner367 (Apr 5, 2011)

There are no parameters for testing with an OHM meter,on these coils.
The only test B/S mentions,is the spark test,with the tester on the plugs.
Basically,if it sparks,it's good.


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## FredM (Nov 18, 2015)

set the multimeter to 20K ohms and place one probe into the spark plug connector and the other to the metal body of the coil body, you should get a reading from 3K ohms to 12K ohms, do the test for both high tension leads, if there is no reading then the HT lead could have an open circuit or maybe an open from where the HT lead goes into the coil, I have come across problems with the plug connector at times too, the metal point and the copper wire have corroded away and this will cause a no spark problem also, the low tension circuit must be working because the engine runs on one cylinder.

I have another suggestion, when you have the engine on the bench, have you thought of swapping the HT plug leads to see if the non running cylinder will run, if the cylinder doesn't fire up, then you can put it down to a mechanical fault if both HT leads check out ok.


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## flchevelleman (Feb 21, 2016)

So help me out here Fred are you saying those cylinders fire at the same time ? I thought the coil fired twice per four stroke like it Fires when one is at bottom dead center in the other one is it top dead center of compression?


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## flchevelleman (Feb 21, 2016)

Tried that! Switched them and now it dies on # 1 BUT it also dies when I pull # 2 too. 
Now I am confused more


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## FredM (Nov 18, 2015)

flchevelleman said:


> Tried that! Switched them and now it dies on # 1 BUT it also dies when I pull # 2 too.
> Now I am confused more


I am assuming that #1 is the good firing cylinder and #2 is the non firing cylinder, so when you changed the HT leads placing #1 on #2 and vice versa, "did #2 cylinder fire up and run and #1 didn't run", I am trying to ascertain if we have a HT lead failure or the coil windings and not mechanical, I think you have said you have fitted a new coil and you still have the problem, geez!! I wish I wasn't so far away over the pond.

I am having to go with JhnGardiner 367and say the coil windings are kaput, have you used the multimeter to check and see if the HT leads have a circuit ??, do you have the Briggs tester, an outlay one doesn't need for around the home, get hold of 2 reasonable size plastic buttons that would have a gap about 1/8" across the holes, attach 2 pieces of copper or soft wire ,one ea. to a hole diagonally opposite each other, make two of these test pieces and attach one wire to the spark plug and the other to the HT lead cap making sure that the cap wire wont drop out when the engine starts, start the engine and observe the spark jumping across the gaps, a good spark will be blue and have a snappy sound, if the spark is yellow/orange, not so good, I should have mentioned this sooner, we would have known by now if both leads are working. 

the coil system is a total loss system and when #1 fires, #2 also fires but at top dead centre of the exhaust stroke, so total loss, nothing to worry about, all flywheel magnetos do this, I once owned a GM Holden V6 (Buick engine) that had three ignition coils with two outlets to each coil and this system worked the same.

I have another web address written by a bloke that has a lot to do with lawn tractor pullers, deals with a lot of topics and a good read on ignition systems which you may find interesting, let me know and I will attach this for you.

Back to you

Regards


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## FredM (Nov 18, 2015)

here is a rough drawing of the button tester


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