A spark plug is said to be "hot" if it is a better heat insulator, keeping more heat in the tip of the spark plug. A spark plug is said to be "cold" if it can conduct more heat out of the spark plug tip and lower the tip's temperature. http://www.ngksparkplugs.ca/tech-info-spark-plugs.cfm

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fuelly link: http://www.fuelly.com/driver/jbw/dl1000

And the bonus question is... How can you tell when your existing plug is too hot or too cold??

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When you think of the long and gloomy history of man, you will find more hideous crimes have been committed in the name of obedience than have ever been committed in the name of rebellion.
- C. P. Snow

In a liquid cooled bike, heat range isn't as big a deal as on an air cooled bike. Liquid does a much better job of removing heat from the combustion chamber, allowing a wider heat range on plugs. That being said, too hot a plug will erode electrodes too fast. In extreme cases, it can cause hot spot detonation or even pre-ignition. Too cold a plug will foul as it won't burn off deposits properly.

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Pat- 2007 DL650A was ridden to all 48 contiguous states. 2012 DL650A is just getting started.
Nicknames for posting ease on my part, Vee = all DL1000s. Wee = 2004-2011 DL650s. Glee = 2012+ DL650s

Too hot a plug will show pitting on the ceramic central electrode and will be colored white-ish gray, too cold will burn sooty. The color to aim for is light tan/gray with the tip looking clean. Lots of color images available with a little searching. Look up NGK or Denso.

Saturn 5