TOPIC:

In the process of going through my "new" bike.

Got to the coils, and did a resistance test on them. According to the manual, the spec for primary winding is 3.2 to 4.8 Ohms. Secondary winding is 10.4-15.6K Ohms.

The 1-4 coil tested 4.2/14.4K.

The 2-3 coil tested 4.2/17.8K.

So, does this mean I need to replace the 2-3 coil? Uh, dumb question?

FYI, I also checked for continuity between the red/yellow wire and spark plug wire, and it checked out negative.

If I do need to replace the coil, I assume my options are to get another old OEM coil on EBay, or replace both coils with new ones. If I go the new route, I assume I should look for 3 Ohm coils, right?

Post edited by: Skyman, at: 2006/12/03 01:12

IMHO the resistance tests are only really good indicators if the measured value is a full order of magnitude different (If someone more experienced than me cares to disagree, by all means do it, I am no expert).

Best way to test a coil is to take the plugs out, and hold them near the block. Spark should easily jump 1/2 inch from plug to block, possibly more. The spark should also be fat, blue, and make an audible crackle.

If your bike doesnt currently turn over, use a friend's bike, or a bike shop could test the coils for you, they have machines made for that purpose.

If you do decide you need new coils, you need to get new ones. They are more expensive, but chances are any used coil that old will be as bad as the ones you have now. I learned the hard way.

What type bike is it? I am not familiar with your "new bike". Perhaps others know which bike you refer to... the KZ1000? In any case, if the one coil is out of spec in the secondary winding, the little bit of extra resistance will cause a slightly less hot spark and probably won't hurt much. I am not familiar with checking continuity between the coil power wire and a plug wire. Can't think of a reason why this would be done... and last, if you buy replacement coils, use aftermarket as used coils tend to be well... used coils and you can't expect another's discards to be better than yours are. Few folks selling used coils put the actual measured primary and secondary resistance values in an auction. If you buy new; get Dyna 3 ohm coils with two outs each or Accel 3 ohm coils with two outs each if your bike is the KZ1000 in your sig. The Dyna coils are easier to fit. Check z1enterprises.com as they offer excellent prices. When I put together a bike, I generally like to use a new Dyna S, new Dyna coils and plug wires. Makes sense to me to eliminate most ignition gremlins on any project.

WG, Sorry I didn't specify. Yes, it is the KZ1000.

The test for continuity between the coil power and plug wire was described in the KZ Service Manual. They wrote that if there was any continuity detected, it was an indication of a short, and therefore the coil should be replaced.

Thank you for your advice. I think I will eventually get new coils, but based on what you wrote, I won't make it a priority for now.

With the purchase of this bike, and all the expenses of getting new parts to whip it into shape, the budget discussions with Mrs. Skyman are getting 'spirited'. So I've got to play marital politics and choose wisely which expenses I will do first.

I'm sure many of you can sympathize.

You don't need new coils immediately and always put "Mrs. Skyman" first! The things that need to be done to make an old bike tip top are not necessarily the ones that most people undertake. Check coil voltages and do the coil repowering mod explained on my web site will generally do more for your spark than replacing the coils. New wires/caps and plugs generally help as well as careful performance of the tune up and maintenance that is recommended in your manual. I also like to replace the carb holders as a matter of course.