So the build date on my 1996 XR600R is Feburary of 1996. Yesterday I changed the plug because it was getting a little harder to start on very cold days. I ask the original owner if he had tried a one step cooler NGK because that is all Pep Boys had and they only get 1.59 for a plug opposed to the dealer wanting $4.50 for the EXACT same plug! Anyway he says not only did I never try a one step cooler, that plug in it came with it from the factory. So this NGK DPR7EA-9 is 12 years old and still works to a degree! I changed it anyway and am going to frame that little bugger! Shoot, I'd be lucky to get a week out of plugs on my RD400s!