Plug reading

Little back ground; '01 426, bought new in June of this year, riding at 6000+ and I was fouling plugs. I took it to Apex Sports here in Colorado Springs, and had jetted using a EGA machine. It ran a lot better, but would\is popping really bad on decel. I pulled the plug and it is sooty black everywhere but on the tip of the electrode and a very small portion at the very end of the part that curves around and sits over the electrode, that part is white to almost silver looking. So I guess my question is, is this a normal plug reading? From everything I have read here, I am running lean, and that concerns me. Any thoughts or ideas on this would be appreciated.

Thanks, Jim

What is your current jetting including pilot screw setting?

My question, on a 4 stroke, what should a properly jetted YZ426 sparkplug look like. I know what one should look like on a 2 stroke, but never really considered what it should look like on a 4 stroke.


'01 DRZ400S

'00 KTM250exc

ice67, I'll have to look at the paper work from the shop when I get home for most of the details, but I do know that I am running 158 main, and a 40 pilot, but as far as needle and clip position and what not I'll have to look.


Jim_H, I have a 2000 426 and the same jetting. It is not too lean. What is the setting on your pilot mixture screw. You may need to turn it out slightly. Have you done the BK mod? My plug was very black before the mod.

I haven't done to Bk mod, because the thought of tearing in to a 900+ kinda' spooks me, but now that I know you have done it aaannnnd, you live in the Springs, how about hooking up some time and both us going over it together.


Jim_H let me know how to get in touch.


I'll be at Aztec this afternoon, white toyota 4x4, or you can call me at 440-2447


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