Norton Coils

I have a box full of 6 volt coils, and would like to see if any of them are worth keeping. How do I check them out with simple tools?

Connect a high tension lead to the high tension port on the coil.
Connect the other end of the high tension lead to a spark plug.
Connect the threaded body of the spark Plug to neg on a 6 volt battery.
Connect a switch (SPST) between the pos of the battery and the primary terminal on the coil.
If the coil has two primary terminals, connect one to neg on the battery.
If the coil has only one primary terminal, connect the metal body of the coil to neg on the battery.
Close the switch for about one second, then open it.
If the spark plug arcs, the coil is worth keeping.

A simple test:
With a VOM, set to Ohm scale .... maximum sensitivity.
Connect VOM leads across primary terminals of coil. If VOM reads open circuit (infinity), coil is definitely bad. If reading is some finite value, the coil may be good, but not guaranteed to spark.

HTH

Slick

If they are the Lucas skinny coils then you should ground the outer metal case when testing (even though there are 2 primary terminals). These often get crushed by the mounting clamps and then the coil internals will either arc or have a direct connection to the grounded case. Those Lucas 6v coils were poor performers (I think they might have been the worst) in The Great Coil Test article by Gordon Jennings in Cycle mag. When that article came out in the '70s I went to the junkyard and bought two shorty Ford coils. Functional but pretty ugly. Used them for 20 yrs or so.

Another thing I've seen is a coil which "works" but the secondary shows open on the VOM. The spark jumps the break in the wire and the plug gap. This is still a bad coil in my book.

Russ

This guy's Youtube "Test your MC's coils" video was really concise and well made - and short! (3 mins) -

https://www.youtube.com/watch?v=rRQ45lT2d3c

The real issue is crushing of coils. The clamps need minimal tightening. Like as little as 2 or 3 lbs. torque. Almost nothing.

From personal experience I know that even if a coil tests OK with a mulitmeter does not mean it is in good condition. That is a good way to check if there is a open connection in either the or secondary circuits but does not eliminate the possibility that the coil will not fail under load or when hot. My bike would start fine when cold but within a couple of minutes would begin to miss. I eventually determined that it was a coil issue when I used a induction type spark testing light (http://www.oreillyauto.com/site/c/detai ... &ppt=C0103).
I could see the spark on one side was weak and irregular. I replaced both coils with a set of PVL's and have not had a problem since.

Pete

Good stuff! I appreciate the feedback.