Octane Question

3 replies to this topic
  • JRide6

Posted February 16, 2009 - 04:38 AM


What octane are you guys running in your stock 426? I just picked up a 02 426 and was reading through the manual and all I keep seeing is 95 octane? The highest I can get is 94 at Sunoco.

  • KJ790

Posted February 16, 2009 - 04:42 AM


The manual is using the RON (research octane number) scale (which is what Japan uses). The US uses the RON+MON/2 rating scale. Since the MON (motor octane number) rating is always lower than the RON, 93 or 94 pump gas in the US is more than enough for that bike.

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  • JRide6

Posted February 16, 2009 - 05:59 PM


Thanks. :lol:

  • grayracer513

Posted February 17, 2009 - 11:36 AM


The U.S. number calculated by the above method is known as the Anti-Knock Index (AKI). It's more complicated because the Government had something to do with it. KJ is correct except that an AKI of 90 is quite probably equivalent to 95 RON, given that an MON of as low as 86/87 matches up favorably. In California, most pump premium has an AKI of 91, and I have no problem running that in any of my stuff.


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