650R spark plug heat range...

2 replies to this topic
  • snaggleXR650

Posted July 26, 2006 - 12:18 PM


I use the standard plug in my 650R, an NGK DPR7E. I noticed in my manual that 'for extend high speed riding' to use the DPR8E. My local Honda shop (idiots) told me that the 7E was the hotter plug.

I do lots of high speed dirt/street riding, like 200miles at 70mph+. I have no problems with my standard plug, but I was wondering if I should be using the cooler 8E plug as the manual recommends.

Anybody have any comments on this?

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  • morewoops

Posted July 26, 2006 - 01:44 PM


the 8 will help, I prosume it is all stock ( motor wise)? if it has head work or a higher comp. piston in it, you will want to put a 9 in it, hope that helps.

  • snaggleXR650

Posted July 26, 2006 - 02:24 PM


Yes the motor itself is stock. Why do you say that I would need a 9 if I had a hopped motor? Is it that a higher compression motor would combust the air/fuel easier and therefore the 'cooler' plug would be adequate, whereas a 'hotter' plug would just generate extra and unecesary heat?

I'm not questioning you, just trying to understand. I've heard of 'hotter' spark plugs, but I've never really understood what different heat ranges were for. I've just always just used the standard plug and never thought much of it. Thanks for the lesson...

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