Topic: 1980 SR500... In search of spark

[ekpent]

  GRRRR- That kind of stuff is maddening.

[Scott S]

This was mentioned in a thread I have on another site:

"Have you tried removing the plug and checking the spark with the bike in high gear and spin the rear wheel ?
sometimes the magnetic field is weak and the kick starter cant spin her fast enough to throw a spark..push starting can sometimes work...."

I have noticed, and I believe I mentioned it before, that the magnetism of the rotor seems weak. I've worked on a few CB/CL350's and the rotor on those bikes will grab a wrench or screwdriver and hold it. I can feel a slight tug on the SR500 rotor, but the field seems weak. Certainly not enough to hold a screwdriver or even an allen wrench.
If the rotor has lost it's magnetism, is there anything you can do about it? Could that be part of my problem?

[Scott S]

I'm beginning to suspect the flywheel. I noticed when working on it that the magnetic field is weak. It barely pulls on a screwdriver or Allen wrench and is certainly NOT strong enough to hold one firmly.
My mechanic has had the flywheel off to replace the stator, but I haven't. I don't know how strongly it pulls when replacing in on the crank/stator.

I found this online:
"Have you considered the possibility that the magnets on the flywheel may be weak or lost their field?
If the unit has been dismantled for any decent period of time and left separated,the field may have degraded.
It used to be recommended to either leave a flywheel magneto all together or put a bar across to preserve the magnetic field.

Good magnets should strongly and quickly pull a spanner held in your hand onto themselves and be a bit difficult to remove it.

Weak magnets will result in a weak and erratic spark.
"

Mine is NOT that strong, from what I remember. I've worked on some CB/CL350's and the rotor on them is strong enough to pull and hold a wrench. My SR500 is NOT.

If the flywheel has lost its magnetism, then what?
The parts fiche lists the flyhweel/stator/magneto as a unit. Even IF I wanted to find a used one, I'd have to make sure it matched my stator, and then there's no guarantee it's good.
Is there a way to re-magnetize the flywheel?

[Scott S]

We did the test today and the stator is wound correctly. Both pick ups attracted the South end of the compass.
We also checked over a few things that had been checked in the past and simply CAN. NOT. GET. SPARK.

Tried spinning the rear wheel in high gear. Tried giving the coil a second ground to frame. Tried eliminating the ground to the CDI. Tried a different plug cap on the new coil. Tried a different gap on the plug. Tried running power straight to the coil. Checked gap on the low speed pick up. And on and on and on.
EVERY single suggestion that I've been given has been tried. Key switch works. RH control works. Main wiring harness tests good. Flywheel and stator are matched. Flywheel has magnetism.

I, and my mechanic, are truly at a loss. I'm open to any suggestions.

Tomorrow, he is going to measure the resistance of the new coil and do a test on the flywheel magnets. I'm wondering if the flywheel has lost magnetism from sitting (I've heard it can happen) and won't produce spark. If that's the case, about my only option is the Powerdynamo set up.

[Scott S]

 Rex's HTC10 coil tests: Primary 1 ohm, secondary  is 8.8 kOhm without the cap, 13.7 kOhm with the cap.

 All of the magnets on the flywheel are strong enough to hold a 19mm wrench against gravity.

 Low speed pickup appears to be grounded properly to the unit frame.

 The tests continue.

[Scott S]

 I'd say that's good. All of the magnets are that strong.

[scottly]

Everything points to a bad CDI. Could you send one or both of the ones you have to someone with a running SR and see if they work on their bike?

[Scott S]

 I've been reaching out on the SR forum and have no takers.
 Someone sent me some instructions for a "pulse test " and I'll try that.

 I may send it all to Rex's and have them test it on their specialty equipment.

[Scott S]

Rex's keeps going back to the stator, specifically the low speed winding. That gives me some pause, because that's the one that Rick's rewound a little fat on the first go round. It was touching the flywheel. We sent it back and he repaired it, but....

 Per Marcus at Rex's: "There’s a ring terminal thats integral to the winding that the mounting bolt goes through, check here.

Another thing I’ve seen - the ‘ear’ that the low speed pick up mounts to breaks off. We’ve seen several bonded and even one welded repair that was so poor there was no earth to the rest of the stator! Check the stator hasn’t been repaired here."

 He also said the coil tests are good.

[Scott S]

 Some random, thinking out loud questions, for when we do the next round of tests.

- If spark is killed by grounding the CDI (yes, we tried the trick of removing the ground wire), if the main harness has some unseen ground....say, along the frame or in the headlight bucket....would that kill the spark?

- If so, would the harness test good for continuity (it does)? Also, the tests that Rex's has for the ignition switch and RH control/kill switch are done at the rear of the bike, back where the stator and CDI plug in. That takes into account the wiring harness. But we've tested each component separately too. Would an unseen ground that kills the CDI have shown up during those tests?

[jgger]

If you test continuity from end to end on a wire and it shows good, it can still be grounded  because the probes aren't connected to the ground. If you check the end to end on each wire  and move 1 probe to the ground/frame each one should show as open if there is no "hidden" ground. I would think.

[Scott S]

 So, if the kill switch is used to ground the CDI in order to kill the bike, a ground anywhere along that circuit, between the kill switch and the CDI, could cause a no spark condition?

[jgger]

Yup. I hope it's that easy for you, that would be great!

[Scott S]

Tested the stator Saturday. With the meter set to AC and hooked up to the White/Green wire and Black wire, we're getting 36V to over 100V AC. So that means the stator is good, right? I've been told that it should be higher output.

Tried to test the signal coming out of the CDI to the coil and get basically nothing. Mili-amps at best. That points to a bad CDI, right?

 BUT.... when I got home with the bike in the truck, the stator was at eye level. That's when I noticed that the ears or tabs on the low speed coil looked a little funny to me. One of them isn't flat or horizontal. And the gap is about .008".



 Also, it looks like this was rewound using different ears/tabs...whatever they're called...than what was on there originally.
 The gap is critical. Not only is it too tight (I think), but the pick up ears/tabs are crooked and not centered over the magnet.
 When the stator was first returned from Rick's, this pick up was rewound too fat and was hitting the flywheel. The shop sent it back and Rick's rewound it. It's STILL not right.





 This was the stock pick up. Notice the ears/tabs and how they're centered over the magnet. You can also see that the gap is different.




 And here's what I have now.





 I showed all of this to my buddy at the shop and he said they'd sent it back to Rick's. But in my opinion, Rick's has had two shots at it already. Rex's has been telling me via email this coil was their suspect and then I find this.
 I feel like I paid for a service (ran it through the shop, so I can't dispute a credit card charge or anything) and Rick's should make it right or refund my money. But I don't think I even want to give them another shot at it.
 Now what? Send it to England and let Rex's fix it right? Try Custom Rewind in Alabama? Can this low speed trigger even BE repaired once it's been screwed up like this?

[calj737]

I think you need to contact Ricks with this new information and documentation. See what he says first. I always prefer to let someone fix their mistakes and make right, that which they’ve done wrong. If he bails on you, then you know your other options. In which case, I’d be shipping it to Rex regardless of the cost. You’re so heavily invested in time that you shuold not screw about any longer trying to save a few dollars, just get it done right and ride the thing.

Or, light it on fire in the backyard and be done with it 

[Scott S]

 I feel the same way but he's done it twice already.

[Scott S]

To add even more mystery and intrigue, I spoke briefly with Rick's, explained the situation and sent them some pics.
They said their technicians notes showed that my original unit WAS GOOD. My shop told them to rewind it anyway. Now it's definitely wrong and that throws suspicions back to the CDI.

So now do I have TWO new/rebuilt parts that are no good!?

The only way to make sure is to send both to Rex's. They have the jigs, parts and test equipment to test and repair properly.
I'm awaiting word back from Rick's.

[Scott S]

 Got the rewound stator back from Rick's, installed it last night...no spark. 


 Stator passes with flying colors. Pulse coil gap is now good.

 I took out the screw on the pulse coil and made sure there was no epoxy on the rear where it touches the backing plate.

 Tested the coil again: good.

 Here's where things get funky.
While I had the test sheet out, I did ALL of the tests again and now I'm getting some funky readings on the key switch/kill switch tests. I have the results written down from before and now my numbers are different.
Especially the "KILL SWITCH OFF, IGNITION SWITCH ON" test. And that one gave me a high reading once before.


 EDIT: set up some leads so I could test it by myself.

 OK, definitely getting something odd on the ignition/kill switch circuit now.
 I set up some leads so I could test it myself and then subtracted the resistance of the leads.

 From Rex's test procedures,  I get:

 1A  0.6-0.7 ohms
 2A  0.6-0.7 ohms
 3A  260*
 4A  infinite

 Test 3A, in my notes, had a star beside it and I got slightly high on a previous test, but nothing like this.
 Maybe something has been iffy and failing up there all along?
 If 3A is bad, which switch is it? The ignition switch or the kill switch? Is the only repair to replace it?


 This was starred before, for reasons I can't remember now.


 In the previous tests, even if I zero out for the leads I used, 3A still showed high.


 But now it's insanely high. What does that tell me?

[Scott S]

 And now I can't duplicate that odd reading. FML! 

 I'm getting the exact same reading across tests 1, 2 and 3 and infinite on 4. But no spark.

 I'm willing to pay someone to fix the damn thing at this point but I don't know of anyone in the area who would work on it.