Spark Plug Question?

[HondaSkidoo]

Hello,

I was reading in my owners manual and it shows Standard plug being NGK DPR8Z and then it states for High Speed Riding use DPR9Z. I also read to help winter cold starting use a hotter plug.

I ride both high speed and slow speed.

What plug are you guys using? Which is best? What is the difference.

Thanks Rich

[GPracer2500]

Here's the technical difference between heat ranges:

http://www.rpmoutlet.com/images/ngkheat2.jpg

For NGK, the higher the number the colder the plug. Colder plugs dissapate heat into the head faster/more easily.

Don't know if that helps you decide. My opinion: A mostly stock EX doesn't seem all that picky about its plug's heat range. Either one will work fine for most people. If you think you really run your engine hard and/or you've got engine mods then a 9 might be a better choice. Otherwise, the 8 is the most appropriate.

If you ride at WOT with high loads often and for extended periods (like racing up a long steep hill over and over) then go with the 9. If you ask your engine to put out most of the HP it's capable of producing for extended periods use the colder of the two plugs specified. Most of the time the 8 is fine and will likely help with starting and throttle response before the engine is fully warmed (especailly in cold temps). If you're engine has mods and puts a lot of extra heat into the engine, the colder plug is prolly the best choice.

If you really must know which plug your engine would prefer, a plug can be "read" to gauge if the heat range is correct.

[HondaSkidoo]

Thanks!! I appreciate the input!

[cals400ex]

for all around use on a stock or close to stock bike i would stick with the dpr8z. you can get more technical with things and actually see how each burns but the average person doesn't wnat to mess with it.

[HondaSkidoo]

Thanks Again! I'm going to stick with the 8s. I just bought a box of 10 off Ebay for $10.00 plus $7.00 for shipping. Beats the dealer price of $4.75 each.

:D