07 450 electrical gremlin...no spark

Little background about the bike.  I bought it in June, rode it a few times then went to Afghanistan the end of July.  Came back in October took it trail riding and the bike ran really hot and starting making some weird metallic rattling noises on hard accelaration.  apparently it hadn't been rebuilt properly prior to me buying it.because my mechanic tore into it and nothing was torqued properly..piston pin ended up elongating the hole in the piston to where it was cockeyed in the cylinder, clutch hub and basket were notched so bad I don't know how they were in one piece, etc, etc.


Now for the problem...I have ridden the bike 3-4 times since the rebuild with no issues until Saturday while riding up an easy hill climb the bike just bogged and died like someone was holding the kill switch.  I had been riding for a couple hours and had a spill earlier in the day but the bike seemed fine until it died and hasn't started since.  I made sure the bike wasn't out of gas and then started pushing it back to the truck.  Got it home and pulled the plug and could tell there was gas in the cylinder so I checked and the plug isn't getting spark.  Upon closer inspection I noticed the ignition coil was melted...see pic:



My mechanic thinks this could have been from when the bike was overheating or from a short of some kind but either way it looks like it caused the plug to arc on the head and possibly short something else out.  I replaced the ignition coil with a new one from my local dealer and still no spark.  I had a buddy with a meter start helping me test the resistance at all the connectors and we aren't getting anywhere.  In the plug on the right side of this diagram we were getting "open" readings where it shows we should have resistance:



My buddy thinks this means my magneto is bad but looking for help and ways to test the magneto or any other suggestions.


Sorry for the long post, I am just at a loss with anything electrical.

test the CDI magneto with an OHM meter,looking for resistance in the coils.The manual will tell you how much but its close to being a dead short,something like 5 ohms(not exact sure).According to your diagram for the magneto you need to check  P&B,Br&G,W&R.These should give you resistance and if one of those dosen't then your magneto needs replacing.Check with the plug pulled apart from the CDI.You can easily check the kill switch by unplugging it and I don't think the neutral or the Throttle position with kill the fire.If you rule out the magneto and everything else then replace the CDI,also make sure no wires melted and shorted if it got hot enough.I'm sure others will chime in on other stuff to try,I'm no expert and may have missed some.

Thanks for the suggestions, I will give that a try and see what we come up with.

So we checked the CDI magneto per the manual and 2 of the 3 coils were producing opens.  The 3rd step in the process for testing the CDI magneto is for charging coil 2(pink and black wires).  That one was perfect at 50 something ohms but the other 2 tests for charging coil 1 and the pickup coil were no bueno...so what does that mean?  Can those 2 coils be replaced individually or do I have to buy a new CDI magneto?

The whole stator has to be purchased as a unit.

Good times.  Looks like it's a fairly easy job once I get over the price of that little sucker!


Should just be part #1 in the attached pic correct?  Praying that part #2 is not needed...


Edited by Lighterknot

#2 is the rotor (flywheel).  Not needed.


Depending on the nature of the problem, it could be that an outfit such as Ricky Stator can repair it for you.  The catch might be shipping, down time, and repair cost that exceed the replacement cost.   Worth checking.


When you're in there, check to see if both bolts are tight, and whether the unit is able to make use of a third mounting bolt.  The '07 was typically bolted down with only two bolts, which sets up a vibration that contributes to coil failures.

Opened it up to take a look and here is what I found.  I thought 2 of the posts were supposed to be wound?


It looks normal to me. Picture's pretty fuzzy, though.  All 4 of those posts are wound, as they should be.  Run the continuity tests outlined in the manual.


Keep track of the O-ring and the two dowel pins:




The whole stator has to be purchased as a unit.


You could also have the stator rewound by someone like Ricky stator, they do good work.

You could also have the stator rewound by someone like Ricky stator, they do good work.



Depending on the nature of the problem, it could be that an outfit such as Ricky Stator can repair it for you. 


must be an echo

Haha, thx guys.  Yeah that picture was crap.  It looks like the protective coating is missing from one of the coils...either way I went ahead and bought a new OEM unit from Partzilla and the bike fired right up.  Now to sell it before something else goes wrong with it...this bike has ended a 27 year love of Yamahas for me!   As soon as I started it up now the water pump is starting to leak from the weep hole.  :(

Edited by Lighterknot

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