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03 450 with no spark.

By dfinn,
in YZ400F/426F/450F/450FX

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dfinn

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Went to the track today. The bike was a little more finicky than normal getting started but once I get it going it ran great. Rode it for about an hour and then went to the truck to take a brake. Let it sit for 20 minutes and then went to start it and nothing. I got it home and pulled it apart and it doesn't seem like I have spark. I'm testing by kicking it over and holding the spark plug to the head, I also tried the holding it to the head bolts. That's correct way to test, right?

I disconnected the kill switch and still get no spark.

What else should I be checking?

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marv02

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Check the spark plug cap make sure it did not back it self out make sure it screwed on all the way to the coil wire it self..

Check the wire conectors makes sure they didn't come apart.,

Check the wire loom that go's along the frame make sure the the plastic coating has not worn through off some where thats either a broken wire or grounding out against the frame.

Ohm the wires out from the stator to the CDI and the coil to wire conectors to double check if there's not a broken wire you cant see and shake the wire at the same time to make sure it not a intermittent short in the wire as you Ohm it out.

Do a coil test and a stator test.

If all of the above dont work is most likley it be your CDI.

Edited by marv02
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dfinn

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Check the spark plug cap make sure it did not back it self out make sure it screwed on all the way to the coil wire it self..

I'm not sure what you mean by this. Could just be me being an idiot but would you mind explaining that a little more? When I pulled my plug out it was threaded at the top.

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grayracer513

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I'm not sure what you mean by this. Could just be me being an idiot but would you mind explaining that a little more? When I pulled my plug out it was threaded at the top.

The cap he's referring to doesn't exist on the 450 as it does on his 426. The 426 uses a remote coil with a plug wire, and on that wire is a screw-on spark plug terminal. Your 450 uses a coil-over-plug, or "stick coil" setup with no plug wire involved.

Download a manual if you don't have one and go over the test procedures laid out there.

http://www.yamaha-motor.eu/eu/services/owner-manuals/index.aspx

http://www.yamahaownershandbook.com.au/?r=0

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dfinn

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Little more info. Replaced plug, not sure that mattered though.

If I kick it a couple of times and then hold the kill switch down it will spark on the first kick with the kill switch down. No more after that. To get to spark again I have to let off the kill switch, kick it a few times, then kick it again with the kill switch down and I get a single spark.

Bad kill switch? I thought unplugging it completely overrode it? I don't think the manual covers this situation.

edit: kill switch continuity tests pass, ignition coil passes primary coil resistance test and secondary coil resistance test, all 3 resistance tests for CDI to magneto check out

The neutral switch doesn't have continuity when in neutral. Could this keep the bike from starting? Any way to override this? Unplugging it made no difference on the spark situation and it sounds like unplugging it overrides this.

Looks like the manual is telling me that the next step is to replace the CDI.

Edited by dfinn
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marv02

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E Bay yes you can get stuck with anouther bad one but I purchased a couple CDI on E Bay before and everyone so far been good.

Plus you can get a great deal on E Bay if you look around for one DON'T buy after market one I think there Pro Comps others say they are junk.

Edited by marv02
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marv02

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I would recheck the wiring I think you have a short some where.

And at least you know it not the CDI chech the wires comming out of the engine case on thats what normaly short out I have found.

Edited by marv02
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dfinn

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wires coming ouf of the case look good. Jiggled and moved them around, didn't change anything.

Would it be worth trying a different ignition coil? Looks like I could pick up one of these cheap from ebay.

http://www.ebay.com/itm/2004-2011-Yamaha-YZ450F-WR450F-Engine-Motor-Cap-and-Coil-Spark-Plug-Starter-/320973712996?pt=Motorcycles_Parts_Accessories&hash=item4abb862e64&vxp=mtr

If it's not likely that's it I don't want to bother though, already bought a CDI for no reason.

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dfinn

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Are you sure you didnt get a hold of a bad replacment CDI.

No. The manual doesn't really give any way to test the CDI that I could find. I don't know that mine was bad to begin with but it was a cheap enough part that I thought it was worth a shot grabbing a used one to try. I wish I had a buddy with a similar bike that I could borrow parts from but unfortunately I don't.

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  • 11 years later...

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