Zong Sierra No Spark...what am I missing?

[ManOfActionDT]

Spud, you have a ton more experience... and thank you for the advice on the tools, if it's not the flywheel...what else is there?

I am getting low and intermittent voltage through the system
I've replaced:
Battery
CDI
Rectifier
Stator coil
Pickup coil
Ignition coil
Spark Plug
cleaned all of the ground connections
disconnected and cleaned all of the connections
All connections show continuity with my multi-meter
All of the resistance values are in spec
Verified that the starter clutch engages by momentarily running the starter motor with the crank case cover removed prior to replacing the crank case gasket.

I'm sure when I find it... it's going to be something I've overlooked... clue me in what have I overlooked?

[Weldangrind]

When you say pickup coil, does that mean the magnetic pickup that is triggered by the flywheel?

[ManOfActionDT]

Yes, one of the three sets of coils on or around the flywheel...I'm referring to the one on the outside of the flywheel that aligns with a "bump" on the flywheel that is supposed to induce a charge in the coil, that charge signals the CDI to fire if I understand it correctly.

[SpudRider]

Originally Posted by ManOfActionDT

Spud, you have a ton more experience... and thank you for the advice on the tools, if it's not the flywheel...what else is there?

I am getting low and intermittent voltage through the system
I've replaced:
Battery
CDI
Rectifier
Stator coil
Pickup coil
Ignition coil
Spark Plug
cleaned all of the ground connections
disconnected and cleaned all of the connections
All connections show continuity with my multi-meter
All of the resistance values are in spec
Verified that the starter clutch engages by momentarily running the starter motor with the crank case cover removed prior to replacing the crank case gasket.

I'm sure when I find it... it's going to be something I've overlooked... clue me in what have I overlooked?

This problem is too complex for me to diagnose from distance without ever seeing your motorcycle. Therefore, I suggest you seek a professional mechanic, preferably a Yamaha mechanic, who will inspect your bike.

[ManOfActionDT]

Spud et all.... Thank you for all of the advice and help... I'll find a pro to take a look at it and hopefully diagnose the problem... and I'll keep you all posted on what they find.

[SpudRider]

You've done most of the work, and have new parts for the entire electrical system. Therefore, a professional mechanic shouldn't have much trouble diagnosing the problem. Hang in there, and please do keep us updated.

[ManOfActionDT]

And Spud, if you're ever in the Seattle area... dinners on me!

[SpudRider]

Originally Posted by ManOfActionDT

And Spud, if you're ever in the Seattle area... dinners on me!

Thank you.

Unless it was tampered with, I seriously doubt the flywheel is bad. However, I am now considering the possibility someone might have tampered with your flywheel. Was your wiring harness damaged? What happened to your regulator/rectifier (R/R), since it was not like mine in the photograph? If someone pulled the flywheel, he certainly might have damaged it. Is it possible the previous owner damaged the flywheel?

[ManOfActionDT]

Since I purchased it in non starting condition.... the possibility is there that it got damaged / abused... the wire harness has seen better days... and the magnet bump out that is supposed to trigger the pickup coil is polished up like it had been rubbing on something.

I must have misspoke the rectifier in your picture matches mine... what brought up the question was the wiring diagram from the Euro service manual I downloaded.

[SpudRider]

I don't know how the flywheel got polished. The bump on the flywheel should not contact anything inside the engine.

If I understand you correctly, the wiring harness appears worn, and you have ordered a replacement. I think it's worthwhile for you to replace the wiring harness, and see if that corrects your problem.

If you are willing to invest about $40 in tools and some time in labor, I also think it's worthwhile for you to replace the flywheel, since you have already ordered a replacement.

[ManOfActionDT]

I'll get pictures of the fly wheel and the polished pick up coil magnet this weekend....

Yes, I know that china bikes aren't known for pretty harnesses... but I don't think they chop and splice like this one is... the continuity checks but the fact there are connections and wires that appear to be part of the harness in your photo that are completely missing from mine makes me wonder...

Looking at the picture of the flywheel holder you posted the width of the holder matched the width of the "polished section"... I wonder if the previous owner tried to pull the flywheel... botched it then sold the Zong to me (ok for 200 bucks its worth the education on trouble shooting alone)

I found a place that says they'll work on it... but it's a drive... so I'm going to install the new wiring harness and flywheel before using them as a last resort... at that point with a completely new electrical system I know I did my best....

[SpudRider]

Replace the wiring harness, and test for ignition spark before you think about replacing the flywheel. I await photos of your bike's flywheel. Please also post photos of your bike's wiring harness, including the 'missing connections.'

[bogieboy]

Given both the mag and pickup are polished, i am wondering if something was loose in there, and possibly messed up the pickup?

[SpudRider]

If you can take some closeup/macro photographs, I might be able to tell you more. Cam timing chains are pretty inexpensive. Therefore, I have replaced the cam chain each time I have done a top end rebuild of my Zong's engine. I have removed my Zong's flywheel twice, and I know the appearance of a good flywheel.

[ManOfActionDT]

Attached are a couple of photos of my flywheel... I hadn't noticed the scarring on the inside of the flywheel opposite the pick up coil magnet, I'm guessing something got loose inside there at one point.