kz 550 power loss

650ed wrote: Check to make sure the Dyna wires aren't touching the cover when it is in place. Maybe dust the inside of the cover with something, install it, go for a ride until the problem occurs, then inspect the inside of the cover for telltale marks on the dusting. Ed

Another thing to try: ride it until it starts cutting out and stop. take the cover off and cool the insides (blow on them) for a few minutes then jump on and see if the problem is gone. If so, it probably is a heat issue.

If you are using used coils from a 1981 Kz550, then you are using the wrong coils. They will overheat the Dyna S. Dyna specifies 3 ohms as the minimum. The 1981 KZ550 coils should be about 2.5 ohms.

so the best thing to do would be replace the coils with 3 ohm coils from dyna and replace the electronic ignition?

michalw wrote: so the best thing to do would be replace the coils with 3 ohm coils from dyna and replace the electronic ignition?

No. The best bet is to diagnose the source of the problem rather that swapping parts without a clue. You stated:

A - the ignition fails when the points cover is ON
B - the ignition does NOT fail when the points cover is OFF

So what makes you believe the failure is related to the coils? Think about it for a second - if the system fails with the points cover on but does not fail with the points cover off the problem would seem to be in the area of the points cover, and that is not where the coils are.

I would first nail down the cause of the problem and THEN replace parts that are at fault or correct a wiring issue if that is the cause of the problem. You could start with my recommendation in my earlier posting. That may not solve the problem, but at least it should eliminate one possibility.
Ed

If the Dyna S is indeed failing from heat, using coils that are too low in resistance can certainly be the cause.

Of course, check the wires since that doesn't cost any money, but eiither way, whether you replace the Dyna S, or keep the existing one, you will want to get new coils (if they are in fact the lower resistance coils from a 1981 KZ550).

You didn't say what year and model you actually had, but if it was one that came with electronic ignition originally, the other option is to use the factory system if you still have the parts for that (pickups, rotor, and igniter). But if the old coils are cracked, you will still want new coils.