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Maxxed out
03-19-2005, 10:06 PM
I can run a couple different sizes of spark plugs in my dirtbike (I know this is a fourwheeler site, but anyway) which obviously have diferent letters on them. My question is what do the numbers/letters actually mean? For instance, I usually run a BR9EG plug, but I fouled it and my friend only had a BR9ES so I used that. What are the pros/cons to different plugs for my bike? Should I choose one kind over the other for certain conditions? Thanks in Advance!!!
Maxxed out
03-23-2005, 01:04 PM
Okay.... No one knows???
stupid driver
03-23-2005, 01:42 PM
alright, they have many different meanings, everything from thread diameter and thread reach to heat rating. Every manufacture differs slightly with their symbols. I would look in your manual, and see what the manufacture reccomends. An example, the difference between a DPR9z and DPR8z is the heat rating. Hope this helps some
zephead400ex
03-23-2005, 01:49 PM
Here's your explination: http://www.ngksparkplugs.com/techinfo/spark_plugs/partnumberkey.pdf
Maxxed out
03-25-2005, 09:41 PM
Thanks for the info, that site helped with the numbers/letters but does anyone know the pros/cons to different plugs for my bike? Should I choose one kind over the other for certain conditions? Thanks in Advance!!!
stupid driver
03-26-2005, 10:43 PM
it basically comes down to the heat rating. I'm guessing that the bike you are referring to is the yz125 that is in your sig. If that is the case, i would run the stock recommended plug; you have not drastically altered your engine internally. if you had a big bore or something of that nature, i would say that the hotter plug would work for you.

Your probably wondering what a hotter plug will do in your bike. Basically, it wont make much difference. All that a hotter plug does is it handles heat better therefore reducing the chances of predetonation. But, at say...two to three bucks for a plug, you might as well get the right plug not worry about it. Thats my .02
cals400ex
03-27-2005, 03:26 PM
the colder plugs are more made for constant high speed riding. i don't think i would run a hotter plug unless it is really cold outside. i would run the stock plug unless your engine is modded.