Ignition coil test needed

 Hi everybody.

A few days I posted about a title issue on a cx500 and you guys were
very helpful (not easy but I can get one).

I also have a 73 cb500 w/ no spark, I get a spark at the points,
voltage up to the ignition coil, and the kill switch is off.

Does anybody know a good ignition test? I don't want to spend $60 on a
new one with out proof of need.

Also anything I should test.

Thanks

 

Service manual has those tests if I'm not mistaken.

 

Stick your finger in the plug wire socket and kick the bike over?  Or,
stick a screw driver in the plug socket and hold it very close to the
cylnder head.  You should see the spark jump.  Ideally you'd pull the plug
and touch it to the cylinder head, but you never know if the plug's bad.
Using a new plug would be best.


Take a 12 volt test light and place it across ground and the coil side of
the points.  It should be off when the points are closed and on when the
points are open (with the key on).  Double check between ground and the
point where the conductor running from the points to the coil connects to
the coil.  Assuming that checks out, you should get the stuffing shocked
out of you when you kick the bike over while holding onto the plug wire
(or get a spark via the screw driver method).  If the low voltage side
works but you get no spark, then you have either a bad coil of a bad plug
wire.

I think,
Robert

 

Off as in "Stop" or off as in "don't stop" (more commonly known as
"run")?


Bad, bad, bad idea. Spell that with a capital 'bad'.


So far, so good. There should be a capacitor (condenser) in there, too.
If it's bad, then the circuit won't work as well or at all. If
everything else checks out, replace the crappedacitor.


Don't do that. If you get it just right, the current could go through
your chest and stop your heart. Your '73 motorcycle might not kick a lot
of current through its sparkies, but a modern bike can be quite
dangerous in this regard. Either way, the procedure is just a variation
on Russian Roulette.

Here's another test to do: Turn the motorcycle off. Put the multimeter
on an Ohms scale, probably 10 kOhm or 100 kOhm. Unplug the spark plug
cable at the coil. Measure the resistance of the coil between the +
terminal and the spark plug. It should not be a short (0 Ohms); it
should not be infinite (no movement of the pointer or a DVM's "over"
symbol). A value of just a few to just a few hundred ohms is probably
not right; I expect thousands of ohms or more.

If this checks out, then the culprit may be a bad plug wire.

If you must do a live-spark test, then unscrew the spark plug, connect
it  to the spark plug cable and that  to the coil. With a well-insulated
(if you don't know what that is, don't do it) glove, hold it to some
ground place away from where the open spark plug hole is going to spew
splodey fuel-air mixture. Run the starter for a second. The spark plug
should make a nice phat spark.

--
Timberwoof <me at timberwoof dot com>
faq:  http://www.timberwoof.com/motorcycle/faq.shtml
Ten Steps to Fascism: http://www.guardian.co.uk/usa/story/0,,2064157,00.html

 On Mar 11, 6:22 pm, offwhitegh...@yahoo.com wrote:

You should be able to use the ohmmeter setting on a multimeter
to check the primary and secondary coils. Without a manual
I couldn't tell you specific resistance values but would guess
somewhere around 1 ohm primary and 6-7 k ohms secondary.

A reading of infinity on either one means the coil's open.