My 15 yz450 fouling plugs

[15thumper]

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]

What specific spark plug (brand and heat range)?

[15thumper]

Stock ngk cr8e

[grayracer513]

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]

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]

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....

[rickallen124]

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 January 22, 2016 by rickallen124

[15thumper]

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]

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]

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]

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]

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]

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.

[Supercooldude]

Hey I’m seeming to have the same problem when I put a new plug in my 2010 Yz450 is starts and runs great than I’ll shut of the bike and it won’t start again I’ll clean the plug and it will start again when I take out the plug it is a blackish color does anyone know what could be causing this ? Is it just running Rich ? Thanks