My 15 yz450 fouling plugs


12 replies to this topic
  • 15thumper

Posted January 10, 2016 - 05:37 PM

#1

So curious on thoughts on this I replaced flywheel on the bike and since that now I'm fouling plugs real quick to the point it won't start, then I change plug and starts right up but will foul the plug after just a short time, the plug is not wet but is black. Thoughts?

  • grayracer513

Posted January 11, 2016 - 07:15 AM

#2

What specific spark plug (brand and heat range)?



  • 15thumper

Posted January 11, 2016 - 10:52 AM

#3

Stock ngk cr8e

  • grayracer513

Posted January 11, 2016 - 11:49 AM

#4

Dry black powdery looks come from weak ignition.  Can be due to rich mixtures, too, but the bike should act up a bit if that's true.  Double check the flywheel is correctly seated all the way on over the key.  People have had an unusual amount of difficulty in doing that on the EFI bikes for some reason. 



  • 15thumper

Posted January 11, 2016 - 04:21 PM

#5

Yeah I've had nothing but issues since I stalling flywheel reinstalled it 6 times making sure it's correct but still having issues, so as of right now put oem back on and new plug so I'll see if it keeps running good or continues to foul out
Never thought putting a flywheel on would be difficult or give me issues

  • grayracer513

Posted January 11, 2016 - 04:27 PM

#6

It shouldn't, but this isn't the first I've seen complaints of various ignition troubles following the installation.  Not sure what the problem(s) are....



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  • rickallen124

Posted January 21, 2016 - 08:43 PM

#7

Let me know what you find as my friend is having similar issues with his '14, foul a plug put a new one in and it runs fine for a while.  He hasn't changed the flywheel on his. I'm starting to think that there may be a coil/stator issue. He didn't start having issues until the weather turned cold either.


Edited by rickallen124, January 21, 2016 - 08:47 PM.


  • 15thumper

Posted January 22, 2016 - 04:44 AM

#8

I ended up putting stock flywheel back on and so far after on ride still good, if it continues to run good I'm thinking the gytr fw was giving me good spark, I also remapped just to make sure I wasn't dumping fuel
That should say gytr flywheel wasn't giving good spark

  • SAKs YAMAHA

Posted January 22, 2016 - 07:23 AM

#9

Is it possible that GYTR flywheels are bad because they weld the weights on rather than using epoxy like stealthy? With the heat from the welding disrupting the strength of the magnets and not allowing a hot enough ignition? I am curious about this, cuz I planned on building my own weighted flywheel. Welding it together seems like the safest strongest route.

  • grayracer513

Posted January 22, 2016 - 08:00 AM

#10

Up until now, all GYT-R and DRD weighted flywheels have been welded ring setups, and none have given any trouble.  New vendor?  Bad batch?  Who knows, but welding the ring per se isn't the trouble. 



  • SAKs YAMAHA

Posted January 22, 2016 - 10:26 AM

#11

Up until now, all GYT-R and DRD weighted flywheels have been welded ring setups, and none have given any trouble. New vendor? Bad batch? Who knows, but welding the ring per se isn't the trouble.


Cool, I was hoping to get your opinion on that. Sorry if I took attention from the OP.

  • mattgill03

Posted January 22, 2016 - 11:26 AM

#12

Had the same problem with my 15 about a month ago. Called the dealership and they said it needs to get to optimum operating temperature before you turn it off. If you run it before optimum and kill it, it has a chance to foul the plug. Something with the amount of fuel and compression when they start he said. Anyway, it has been fine since. It has been cold but I don't have a flywheel weight like you do. 



  • grayracer513

Posted January 22, 2016 - 12:11 PM

#13

Had the same problem with my 15 about a month ago. Called the dealership and they said it needs to get to optimum operating temperature before you turn it off. If you run it before optimum and kill it, it has a chance to foul the plug. Something with the amount of fuel and compression when they start he said. Anyway, it has been fine since. It has been cold but I don't have a flywheel weight like you do. 

 

That's been true since the YZ400F.  Start them and don't run them up until they reach normal temp ranges, the plug never gets hot enough to clean itself.  The EFI bikes don't have a choke (the "cold start knob" just opens an air passage to raise the RPM) because the ECU compensates for low temperatures with more fuel all by itself, so it's even worse.

 

Just a bad habit.







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