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how to test ignition coil

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Josse:
Can anyone please explain how to test a  400/4 ignition coil using a multi meter

thanks Josse

Johnwebley:
do you know the values/readings you want ?

 basically use the both power leads,and see if you have a circuit,

and the same ,with the plug leads remove the plug caps and check if you have a circuit,

its worthwhile renewing old plug caps as they tend to "burn out" with a greatly increased resistance  ,

Lobo:
Hi Josse,

Within each coil there are two separate windings... the primary winding (a few hundred turns) & the secondary (HT) winding @ a few thousand turns. For the coil to work each winding must be complete. So... as John says, set your multimeter to the continuity scale & for test (1) put the 2 probes across the primary winding (yellow & black/white or blue & black/white),  and for test (2) across the secondary winding (ie the two spark plug caps)

In both cases there should be a complete circuit.

The manuals (I have) do not quote typical resistance readings.... and I can only suggest you test both coils and check that the results are similar (rather like compression testing). If they are ... well good.

Sadly the coils / leads / caps all 'degrade' due age, ie even if the results match you're not home & dry. Perhaps a kind member with new / known good coils could supply some readings.... I'm away from my bike til Feb unfortunately so can't help in the short term here.

Finally, why not lop the tip off a spark plug and in its place wind a stiff copper coil abouts the threads & then to a new tip... and crank the bike. If you can get a spark at (say 5mm) I'd reckon all's well.... the test equipment mentions 7mm. (But honestly I'm a bit out of my depth on whether this test would work / be valid ... Bryan...OddJob?)

Simon

Bryanj:
If you remove the side electrode from an old plug and put this in a cap you should be able to get at least a 5mm gap jumped. The book does say 7mm and the testing machine used to overdrive the coils a lot I.E. make them spark a lot faster than at tick over so was a lot better than a kick over test.

I have had Lucas coils fail when they got hot but never a Honda one, if fact I have only changed them due to lead damage/too short or physical damage in an accident

El__burro:


--- Quote from: Lobo on December 20, 2014, 09:02:11 AM ---
Set your multimeter to the continuity scale & for test (1) put the 2 probes across the primary winding (yellow & black/white or blue & black/white),  and for test (2) across the secondary winding (ie the two spark plug caps)

In both cases there should be a complete circuit.

The manuals (I have) do not quote typical resistance readings.... and I can only suggest you test both coils and check that the results are similar (rather like compression testing). If they are ... well good.
Simon

--- End quote ---
Sorry to jump on this thread but it is exactly what i was looking for.
I have done the test Simon suggests above and it gives me continuity when i connect either the blu and black/white or the yellow and the bl/w.
My issue is when i connect the ht leads from the same coil, they both read about 14.0 ohms but no continuity.
Faulty?

Thanks
El__burro
Cb750 k2

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