TOPIC:

lumbee wrote:

Ok, I feel like I'm making progress! Actually saw spark on the plugs today 

JR, good call on downloading the GPZ750 manual. I found this test procedure and when through it and indeed, I laid eyes on spark on all the plugs. So, this is telling me the issue is with the pickups not sending a signal. I did resistance tests on the pickups and they passed. Is there a way I can force the pickups to fire if I touch a ground wire to the pick up lead should the points fire?

 

You can't ground the pick ups to force them to fire, however the test you have performed does suggest the pick ups are at fault. The only way to manually active the pick ups would be to unbolt the mounting plate they sit on, move them clear of the trigger and then pass a metal object (screw driver shaft, drill bit etc) over the pick up. If the pick up is working this should trigger the igniter

@howardhb good eye, and yes, I noticed that and had planned to address it, though I was not sure how. JB weld is a good idea. So odd! Almost like something pulled on the wires, but the wire insert seems firmly in place, it is just the insulation that's pulled back.

@wookie, I tried activating the pickups by touching something metal to the raised area close to the spark advance (the piece that spins) and go nothing. How is that different than what you are suggesting? Thinking about it more isn't it the magnetic field that passes by the pickup that causes the signal to spark? Wondering if I would be using a magnet to try and get it to fire.

Thinking more about this, when I got the bike, all of the goodies under the right side cover were rusted to beyond recognition. I pulled everything apart and cleaned it with a brass brush and cleaner, then gave it a rattle can spray bomb to prevent future rust. Wonder if the coat of paint could be preventing the magnets from making good contact, and hence a weak magnetic field as the advance passes by the pickups ?

@wookie, I tried activating the pickups by touching something metal to the raised area close to the spark advance (the piece that spins) and go nothing. How is that different than what you are suggesting? Thinking about it more isn't it the magnetic field that passes by the pickup that causes the signal to spark? Wondering if I would be using a magnet to try and get it to fire.

Sweeping a piece of metal across the pick-up is simply simulating the action of the advancer. The advancer interrupts the magnetic field generated by the pick up coil - the advancer is simply a piece of metal not a magnet.

The below might help, I suspect corrosion at the pick-up mounting points may be your issue

 

When I repaired mine, I completely disassembled (to clean) the pick-up mounting plate, magnets and all.
I failed to mark the original position AND orientation of the "C" shaped magnets that are mounted behind the main pick-up plate.
I believe they are magnetically polarised about the centre of the "C" shaped magnets (see the dotted centre lines in my picture below)

I inadvertently re-assembled the magnets incorrectly, and the result was no spark!
When I examined the magnets carefully, I could see which face should be facing outwards: i.e. away from the mounting plate.
I flipped one magnet over and, VOILA, spark!

*NB* the magnet mounting screws MUST be non-magnetic (Brass)

Not sure if you disassembled yours... but If you did, try flipping one magnet over (about the centre line)

 


Also, I read that you disassembled the advancer.... Note that the cam shaped "trigger" lobe can be incorrectly assembled, 180 degrees off.
This will cause the sparks to occur on the exhaust stroke and not the compression stroke
( ask me how I know )

H.

@wookie cleaned everything up and checked for good ground on the pickups and that's all good (still no spark)

@howardhb, this is helpful, thanks! I have had a sinking feeling all along that something is just not right with the assembly of things around the pickup and I'm hoping this may be it. I did notice the magnets have a white line scribed on one side, though I'm not sure if this would indicate which way they should face. At any rate, I'll pull things apart this afternoon and change the orientation and see if that helps.

Ok, I'm a little farther down the road. After some re-jiggering of the magnets, I managed to get spark on one set of coils, but not the other. From everything I can tell one of the pickups is just not firing even though all of the tests I have done say its good. Unless I have an epiphany over the weekend I'll probably get another set of pickups from ebay and see if that changes anything.

Regarding the magnets and polarity, I found this page: gpzweb.s3-website-us-east-1.amazonaws.co.../PickupAndRotor.html Very good resource on the matter. I am also attaching a pdf version of this page here in case this URL ever changes or goes bad.

I'm not surprised you found Lou's( loudhvx ) website. He is dearly missed.

F64 wrote:

I'm not surprised you found Lou's( loudhvx ) website. He is dearly missed.

Amen. I am surprised his website is still up. I think it would be a good idea to download or copy everything we can before it all disappears.

Looking at buying this unit as a replacement for the pickups: www.amazon.com/Premium-Electronic-Igniti...asaki/dp/B09H5JWHMN/

I am unsure about the wires, specifically the single red wire. Stock unit has red <> yellow and blue <> black. Any suggestions on how I could map those to these wires?

lumbee wrote:

Looking at buying this unit as a replacement for the pickups: www.amazon.com/Premium-Electronic-Igniti...asaki/dp/B09H5JWHMN/

I am unsure about the wires, specifically the single red wire. Stock unit has red <> yellow and blue <> black. Any suggestions on how I could map those to these wires?

As I understand it this is a Chinese copy of a Dyna-S ignition which replaces the original pick-ups and the igniter. The red is an "ignition live" and the black and white go to the negative (switched) side of the coils
 

OK, that's what I was thinking, I just wanted some confirmation. I'm going to give it a go. I'll probably have questions once I get it and do the install.

So weird though, just to recap, I consistently get spark from one of the pickups (blue/black) but not the other. I could swap the wire up at the coil and get spark from either 1/4 or 2/3. I completely removed the wire bundle and pickups from the bike to inspect it and after reinstalling it I had a moment where I had spark intermittently at the red/yellow pickup, but it was inconsistent. even cut/spliced new wires into the bundle for the red/yellow wires thinking maybe there was a short along the length of one of the wires somewhere, and same thing. Spark intermittently, but could not find any rhyme or reason as to when it would fire.