spark plugs?

4 replies to this topic
  • zaxcar1

Posted April 06, 2008 - 02:50 PM


i have a ngk br8e plug in the bike now. i was told i could run a cooler br9f. would that have any porblems?

  • zaxcar1

Posted April 06, 2008 - 02:53 PM


sorry that was a cr8e and its for a 426

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  • grayracer513

Posted April 06, 2008 - 03:34 PM


You can if you like changing plugs so much that you want to do it more often. The 9's are too cold to stay clean in your engine unless, maybe, you're running super moto with a 13.5:1 compression ratio on a long track in the summer. You will foul them often.

A colder plug WILL NOT make your bike run cooler. The heat range of a spark plug is a measure of how fast the heat of combustion is carried away from the center electrode. If the plug is too cold, it will never burn away the fouling deposits that try to build on the porcelain, and it will foul. If it's too hot, it will retain too much heat, probably crack the insulator or burn away the center electrode too quickly, and possibly cause pre-ignition. Stay with the CR8's. They are right for your bike.

  • sirthumpalot

Posted April 06, 2008 - 03:42 PM


To oversimplify what grayracer said, the spark plug heat range basically referrs to how hot the center electrode will be during operation. Most commonly, if it's too hot then it can cause pre-ignition (knock, ping) or if way too hot possibly dieseling, too cold and it will foul easily. Rarely is there reason to change from the stock plug on a mostly stock motor.

  • William1

Posted April 06, 2008 - 03:49 PM


My bike came with a 9 in it. It fouled, porcelain was always wet. I run a 8, comes out nice and dry.

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