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Checking coils. It's time I learned
Posted: Sun Feb 08, 2015 8:17 pm
by Coyote
Seems like all the manuals give you the values, but not really how to go about it. Consequently I have never checked a coil in my life. It's really something I should have learned long ago. So here goes.
How do I check the primary coil? From where to where?
What is, where is the secondary coil? How do I check it? From where to where?
I have 2 multimeters My 40 year old radio shack is more accurate than the whiz bang I bought at Sears a couple of years ago..
My old trooper Micronta was an old radio shack brand. So was Realistic. Alligator clips are slip on friction fit over probes.

Re: Checking coils. It's time I learned
Posted: Mon Feb 09, 2015 12:11 am
by pearljam724
Put the positive end of your meter into the positive leads of the coil you want to check. Which are the orange wires leading to the connection socket. Put, the negative lead of your multimeter into the coil spark plug lead of that same coil you are checking. Set your meter to ohms. Ohm resistance should read very close to 4 - 4.5 ohms. A 3 ohm reading is ok, but not quite up to par. If it were me, I wouldn't even bother testing them when you can buy 3 universal coils that have the same ohm rating as your originals. They are 40 years old. I would just replace them. These and an variation of the ones I posted are all over the Ebay. If you look, most likely at a cheaper cost also. These are universal and the mounting holes are dead smack the same as GT coils. Very easy to wire, etc. I put them on my 750 and it made a world of a difference in reference to starting. You'll need to find the ones that are a single coil tower. Which means each coil has one spark plug lead just like the GT's. These are a double tower coil. I've seen the single coil towers as low as $15 a piece.
http://www.ebay.com/itm/Fit-For-Yamaha- ... 18&vxp=mtr" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;
Re: Checking coils. It's time I learned
Posted: Mon Feb 09, 2015 12:20 am
by pearljam724