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Spark Plug Failure

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I was wondering if anyone has had this problem with spark plugs. I bought a new Yamaha YZ 250X. The recommended spark plug is a NGK BR8EG. After 5 hours or so the spark plug just "dies." It wil be completely dead. Not fouled, they just won't spark at all. I came across a fellow yesterday with the same bike and he couldn't get it to start. He was having the same issue. I put a new plug in and his bike fired right up. He had ridden about the same amount of time. Any thoughts on this matter?

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Are you buying spark plugs of Ebay or Amazon?  (lots of counterfeit junk on there)

 

I'm surprised Yamaha doesn't recommend the fine tip Iridium version: NGK BR8EIX

same heat range but better resistance to fouling and longer lasting.

Edited by mlatour

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I've been buying them from NAPA and O'Reilly Auto parts stores but thanks for the tip on the other plug. I'll give it a try.

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I’ve had several YZ’s and 2 250x’s and I’ve only fouled plugs on one of the YZ’s. The X should be close enough on stock jetting that you shouldn’t foul plugs.
On the YZ that fouled plugs it happened several times when I tried to clean the top end out after some tight single track. The bike sputtered and I tried to ride it hard to clean it out. It fouled every time like that. If I slowly cleaned it out by slowly accelerating a little at a time it never fouled.
What type of riding are you doing when it fouls?

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The problem is not fouling. The problem is that the plug just dies. It won't spark at all. The bike shuts down like you were holding the kill switch but a fresh plug will fire the machine up on the first kick.

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Just spit balling but does the plug have the screw-on terminal or the solid terminal tip? I've had the same thing happen when using the screw-on tip becomes loose. I only use the solid terminal tips because of this.

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18 hours ago, TobyJuan said:

The problem is not fouling. The problem is that the plug just dies. It won't spark at all. The bike shuts down like you were holding the kill switch but a fresh plug will fire the machine up on the first kick.

I do not understand this statement, when your spark plug is fouled it does not Spark

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Jet right, use the EIX, and never replace a plug all season, and even more. 

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Had a friend's son's X that had the same issue and his was where he was getting his fuel went through six months of fouling plugs and changed his fuel station and problem was solved and as has been said Jetting and the EIX plug  are very possible solutions . Good luck .

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