Pickup magnet polarity

This came up in another thread so I thought I'd post some info on the magnet polarity on the pickups for the early Kawasaki electronic ignitions.

The polarity affects the signal polarity and magnitude, so they must be installed correctly.

The magnets should both be identical. To test this, try to stick them together. Stripe-to-stripe, they should repel. Stripe-to-blank they should stick.

EDIT:
New procedure for checking pickup polarity:
home.comcast.net/~loudgpz/GPZweb/Ignitio.../PickupAndRotor.html

Here they are on the plate. Notice the white dot. Not all magnets will have the dot. But if you look very close, they will have a bit of the stripe visible. It can be seen on this photo just below and to the right of the dot.


Post edited by: loudhvx, at: 2007/05/04 00:33

EDIT:
New procedure for checking pickup polarity:
home.comcast.net/~loudgpz/GPZweb/Ignitio.../PickupAndRotor.html

Here's the full assembly viewed from below, note the white dot is below the yellow/red pickup.



(This is a different unit. The tip of the white stripe is not particularly visible on this one.)

Post edited by: loudhvx, at: 2007/05/04 17:20

Here is the view from the top. Notice the white dot on the top magnet is above the black/blue pickup. On this particular unit, the tip of the white stripe is visible as the little white area above the white dot.



Post edited by: loudhvx, at: 2007/05/04 00:37

And since we're on the subject of getting polarity correct, here's the kz550 rotor. Notice the point of the rotor points toward the "TEC" logo stamping. The rotor can go on two ways. Pointing toward the "TEC" logo is the correct way. If the bike was running with the rotor pointing the other way (180-out), then some wires must have also been swapped.

On the smaller fours 550/650,
The left-hand pickup (aka rear pickup) with blue(-) and black(+) wires, fires the right-side ignition coil which has a black wire to it. This coil fires cylinders 1 and 4.

The right-hand pickup (aka front pickup) with red(-) and yellow(+) wires, fires the left-side ignition coil which has a green wire to it. This coil fires cylinders 2 and 3.



On the bigger bikes 900/1000, the ignition coils may be on opposite sides of the frame.

What are the magnets for? The twins don't have any magnets and they seem to work fine, although the pick ups are a little different.

If the magnets are on all the four cylinder models, then doesn't that mean we can't use the four cylinder pick ups on the twins?

Will that have any effect on using the four cylinder rotors on the twins?

steell wrote:

What are the magnets for?

They create a magnetic field. This field is directed through the center of the pickup coil via the steel super structure. The rotor completes the path for the magnetic flux. During rotation, the tip of the rotor comes closer to the pickup. As it moves closer, the magnetic flux density increases. This change in flux produces an increasing EMF in the pickup coil. As the EMF passes a certain threshold, the dwell begins. As the tip passes the pickup, the signal suddenly changes polarity because the tip is now moving away from the pickup. The change in polarity triggers the spark.


steell wrote:

The twins don't have any magnets and they seem to work fine, although the pick ups are a little different.

Are you sure? I suspect if you put a screwdriver near the center of a pickup, it will stick. Often, the magnets are integral to the pickup so you won't know it's there.



steell wrote:

If the magnets are on all the four cylinder models, then doesn't that mean we can't use the four cylinder pick ups on the twins?

If the twins have no magnets in the pickup, then yes, they work on a different principle.


steell wrote:

Will that have any effect on using the four cylinder rotors on the twins?

Difficult to say without direct knowledge. It's possible to create the field with a DC current. Then the rotor would work the same way.

If the twins have no magnets in the pickups, then a 4-cyl igniter won't work on a twin.

Post edited by: loudhvx, at: 2007/04/27 23:07

Cool!! I learned something new today

I don't know if the 440/750 twin pick ups have magnets in them or not, but based on your explanation I think they must have. I'll check tomorrow and confirm it.

Thanks for explaining it.

I should mention that the pickups and magnets can work in other configurations as long as some of the wiring is altered accordingly, but the way I describe here is the way that most likely came from the factory, and is how it should be setup.

Also if oriented wrong, the motor may still fire up under certain incorrect wiring schemes. But it may not advance properly and the motor may just die when the throttle is opened.

If it will run with the magnets oriented incorrectly, the wiring errors must be corrected so the magnets can be put back to factory orientation.

Post edited by: loudhvx, at: 2007/05/04 17:26

My photos were deleted when my blank posts were deleted. I have to re-post them here to have the photos in the upper posts work.

This post doesn't appear to have a photo, but if it gets deleted, the photo that it holds will also be deleted. Then one of my above posts, which is also calling up this same photo, will also lose the photo. Mods, please don't delete this post.

Post edited by: loudhvx, at: 2007/05/04 00:29

Thanks for posting this information.

loudhvx wrote:

My photos were deleted when my blank posts were deleted. I have to re-post them here to have the photos in the upper posts work.

This post doesn't appear to have a photo, but if it gets deleted, the photo that it holds will also be deleted. Then one of my above posts, which is also calling up this same photo, will also lose the photo. Mods, please don't delete this post.<br><br>Post edited by: loudhvx, at: 2007/05/04 00:29

The pics got deleted because I screwed up and didn't uncheck the box that deletes them.

I apologize.