Does anyone know when and why you should replace your spark plugs?Also, how do you tell the difference between a cold and a hot plug?

 

Cold and hot plugs are more of an issue for two strokes, just get an oem replacement from NGK. As for when to replace the best thing to do is remove the plug and check it for corrosion and buildup. If you can clean it and regap thats great but when it gets looking ugly its time to replace. I always have an extra one or two in the tool box anyway. Sometimes I'll rotate two plugs cleaning and regapping while the newer one is in then swapping after a few rides.

 

To educate yourself about spark plugs, go to the NGK web site. And, see the spark plug section on this site-- http://www.dansmc.com/MC_repaircourse.htm

I change my plugs more often than I need to. They are cheap, so it's no big deal to me if I change them before they need it. The exception would be Irridium plugs, which are more expensive but will last a very long time.