How to test the coil?

aaron7 · #1 09-19-2009, 06:35 PM

I have no spark. Points look fine. Plugs are good.

Removed the coil and was wondering how to test it with a multimeter and what the readings should be.

aaron7 · #2 09-26-2009, 02:29 PM

Can someone with a running bike tell me what the resistance is between the two leads? And then maybe each lead to the plug wire?

I think that's how you test it but I don't have any good coils to base the proper readings from.

SixtyFiveCA95 · #3 09-26-2009, 03:59 PM

Most coils seem to have about 3 ohms resistance. Most likely, that's what it should be.

SixtyFiveCA95 · #4 09-26-2009, 04:01 PM

Actually, probably closer to two, since these bikes are 6 volt.....

aaron7 · #5 09-27-2009, 07:31 AM

Between the two leads or a lead and the plug wire or what?

SixtyFiveCA95 · #6 09-27-2009, 07:53 AM

Pretty sure that you use the leads. Here's some stuff I found about the subject. It would probably be more like 2-3 ohms for a CA95 coil instead of the 3-5 listed here, but the instructions sound right:

Basic coil tests are for Primary and Secondary ohms (resistance) values and I.B. or an Insulation Break meaning you have a short.

Refer to your owners manual for what type of coil you have. Different models have different ohms ranges.
This test would be for a typical 3-5 ohms single lead externally grounded coil. You can usually identify an Externally grounded coil as they are grounded by the mounting fixture itself.
TOOL REQUIRED - VOLTMETER that will read ohm values
1. DISCONNECT THE BATTERY NEGATIVE CABLE
2. If the coil is in the bike disconnect wires from the two terminals to isolate it.
3. Once you set your Voltmeter scale to ohms connect the red and black leads to each terminal. You should read between 3 and 5 ohms if that is the spec for your bike. You have now tested the primary circuit of your coil. If you read 0 ohms replace the coil, you have an open circuit or break in your coil winding.
4.Now take your black lead off one terminal and connect it to good ground, battery negative cable or non-painted frame bolt. Your meter should now read 0 or OFL (off line). If you do get a reading here your coil has a break in the insulation and is shorting out. Your only option here is to replace the coil.
5. Repeat step 4. for the other secondary terminal. Red on terminal, black to ground. It should also read OFL.

Another quick test option regardless of type of coil is to check Volts going to the coil with battery connected. If you have a 12vdc system and you are getting close to 12vdc at the coil terminal and nothing is coming out of the coil you either have a bad coil or connection.

SixtyFiveCA95 · #7 09-27-2009, 08:01 AM

Or you could take the coil off, and take it to an automotive or motorcycle repair shop where they have a tester made for coils. They might not even charge anything.

SixtyFiveCA95 · #8 09-27-2009, 08:19 AM

Key position is a very important thing with these bikes. Mine would only start on one of the key positions. It wouldn't get any spark or voltage with the others. Third position (dot) from last on the left side of the switch. The position right in the center. You might just have the key in the wrong position.

aaron7 · #9 09-27-2009, 01:45 PM

True... there's like, 3 red dots, a black dot, and a non-painted dot! haha

SixtyFiveCA95 · #10 09-27-2009, 01:58 PM

And you have to have a battery with these things to really get any spark. 6 volt. Even a lantern battery will work, at least to get it running. Your CT200 batery would work.

aaron7 · #11 09-27-2009, 01:59 PM

Oh really? Hmm... I bought a new OEM replacement (the WISCO one) but didn't want to fill the acid till the bike was ready to ride.

SixtyFiveCA95 · #12 09-27-2009, 02:00 PM

Isn't your CT200 a 6v bike? That battery would provide enough power to fire it up.

aaron7 · #13 09-27-2009, 02:02 PM

Yes, it is, but batteries start to die soon as they are filled with acid. I hate to fill the battery and end up not riding the bike for a year... then having to buy another battery.

I'll try the lamp battery idea.

SixtyFiveCA95 · #14 09-27-2009, 02:12 PM

Then just go with the lantern battery. I used a cheap $3.00 eveready one to get mine going. Fits right in the battery tray. About the same voltage and amp rating as a regular battery. Run some wires from the terminals to the battery cables. Be sure to check your fuse on the + cable to see if it's any good. Put the key in the center position. A couple of kicks and a little bit of gas in the carb, if it's anything like mine was, it'll fire up at least for a few seconds that way.

SixtyFiveCA95 · #15 09-27-2009, 02:23 PM

You could always use a battery tender and keep your battery charged year round. I did that with my other bike.