Eating spark plugs yz426f


7 replies to this topic
  • Yammer-Hammer

Posted October 23, 2013 - 07:13 AM

#1

Hey all, my 426 has been eating spark plugs, i did the BK mod so i have a 1 second squirt duration, and ive been a cr7e plug in hopes of it lasting longer.   So the bike only fouls the plug on startups, and no i do not twist the throttle.. the bike will start, run for like 10 seconds and die, so i will pull the plug and find that its soaked, and is covered in soot..... I feel like my jetting is spot on, here is the jettting info

Pipe: stock 
Main: 165
Pilot: 45
Kneedle: OBEJP clip in 4th
Elevation: 50 - 1000ft

Temp: 30f - 60f
Humidity: 70 - 100%
Air filter: stock, (will be replacing with twin air in a few days)

PLEASE help me with this bullshit, i am at a loss, and ive compared my jetting with others jetting in the user jetting data base on this website.... BTW, i dont race the bike, i lug it in the woods like 1/4 throttle, but i do get to open her up on the straight aways.


Edited by Yammer-Hammer, October 23, 2013 - 07:17 AM.


  • grayracer513

Posted October 23, 2013 - 08:02 AM

#2

What size is the starter jet?



  • Yammer-Hammer

Posted October 23, 2013 - 07:59 PM

#3

What size is the starter jet?

72


Edited by Yammer-Hammer, October 23, 2013 - 07:59 PM.


  • Thommo_400f

Posted October 24, 2013 - 12:34 AM

#4

Try checking your pilot air jet. If it is blocked it will cause it to be rich and foul easy. Just pull it out and blow compressed air through the passage.
You can run without PAJ as a test. Bike will tend to pop a bit more on decel to indicate it is leaner.

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  • grayracer513

Posted October 24, 2013 - 06:47 AM

#5

And the starter jet and all its passageways are clear?



  • Yammer-Hammer

Posted October 24, 2013 - 07:37 AM

#6

And the starter jet and all its passageways are clear?

I will take a look at it when i get home, i just remeber i shot carb cleaner down both the pilot air and main air jet,but ill pull it out and shoot 150psi down the passages and see if that helps, but could there be any other problems?  I mean the bike starts first kick, insnt that an indication that everythings dialed in?


Edited by Yammer-Hammer, October 24, 2013 - 07:43 AM.


  • grayracer513

Posted October 24, 2013 - 08:52 AM

#7

It dies after ten seconds. Isn't that an indication that it's not?

 

You may have an electrical problem, but if so, it sounds intermittent, and those are a pure booger to chase down most of the time.  So, it's prudent to rule out everything else that's easier to look at before you start fiddling with that.



  • Yammer-Hammer

Posted October 24, 2013 - 06:01 PM

#8

It dies after ten seconds. Isn't that an indication that it's not?

 

Only every now and then it does that, i just adjusted my valves, they were tight (.099mm) on all 3 intake, now there .127mm, (i lapped the shims to get it spot on .127mm).   So ill see if that fixed it (dont see how tight valves could cause that, but they kneeded to be adjusted)  But anyway, i mean it starts first kick cold and 1st kick when hot, so wouldnt that be an indication that its dialed in? its just that every now and then the plug fouls when its cold and that causes it to die after it idles for a bit.


Edited by Yammer-Hammer, October 24, 2013 - 06:02 PM.






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