coil choice with points to electronic switch

Looking in the Clymers manual, I see that electronic ignition coils have lower resistance readings as compared to the points ignition coils that came with the earlier model bikes.

I replaced the points on my '78 650 with an electronic ignition from a 550, and a 750 ignitor. I have the stock 650 advancer unit. I am using the stock coils that were running with the points.

Per the Clymer manual the readings for the points coils are 4.0 ohm primary, 23k secondary, (mine tested similiar) however readings for the electronic coils should be 1.8-2.7 ohm primary and 12-18K ohm secondary.

Will using my "points coils" cause me a problem? I just noticed this and have been running this setup for almost 3000 miles. The engine runs great, better than with points. I am experiencing no problems now, but I want to change things if I should.

It's not a problem as long as your bike runs fine. In fact, higher resistance coils put less stress on the ignitor.

The elctronic ignition has slightly less dwell than points, so at very high RPM, the higher-resistance coils may have a weaker spark. If you can rev to redline under load (4th or 5th gear), with no stammering, then you're ok.

That being said, 30 year old coils can fail anytime, especially after rain storms. That's when you want the 3 ohm Accels or Dynas.

The ignitor is the weak link, but you can make your own for about $30.

www.geocities.com/loudgpz

loudhvx wrote:

It's not a problem as long as your bike runs fine. In fact, higher resistance coils put less stress on the ignitor.

That's good news

The elctronic ignition has slightly less dwell than points, so at very high RPM, the higher-resistance coils may have a weaker spark. If you can rev to redline under load (4th or 5th gear), with no stammering, then you're ok.

It's been awhile since i wanted to go that fast, i'll try it some day

That being said, 30 year old coils can fail anytime, especially after rain storms. That's when you want the 3 ohm Accels or Dynas.

The ignitor is the weak link, but you can make your own for about $30.

www.geocities.com/loudgpz

The ignitor is the one part I don't fully understand. It connects the pickups to the coils, but what is it doing ? And how important is it to have the right one? I really just chose one from a 750 as it was available and I thought it the closest fit , there weren't any 650 ignitors when I wanted one.

Thanks for the help!

Simple non technical answer

Think of the igniter as the points, and the pick up coils as the cam lobe that opens and closes the points.

Basically, on the KZ's with mechanical timing advancers, the pick up coils just tell the ignitor when to fire the coils.

What Steell said, and most of those early KZ ignitors (using mechanical advance) are the same internally.

Thanks for your help guys!