Spark plug difference on 426

I replaced my spark plug for the first time since I have owned the bike this weekend. I got a new plug from the dealer and it was a NGK CR9E. There was no problem with my old plug just some preventative maint. Well i pulled the old plug out and it was a NGK CR7E. What is the difference if any between the 2 plugs? I used the 9E from the dealer and worked fine, just wondering for future reference. Thanks :D

The number represent a heat range, which is determined by the exposure of the ceramic cone.

Additionally, I would stick with the factory heat range unless you have a reason to run colder or hotter. And, the EK plugs (double electrodes) are better than the standard Es.


the CR7E is a hotter plug. the lower the heat range number, the hotter the plug runs.

The NGK CR8E is what the manual calls for on my '01 YZ426F.

Sorry to open an old thread but I have a ? Hope some one can help me. My '01 426 now has a CR9E and I have a new CR8EK. My question is what does the K mean. The manual says to use CR8E.

The K indicates it is an iridium spark plug. It's the same heat range as the CR8E, but with the improvement of a precious metal electrode. The plug is less prone to fail to fire due to partial fouling, and will make the bike start more reliably. It should also last a lot longer. Perfect for your bike.

Thanks gray for the reply.

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