My spark plug reading makes little sense after viewing many TT posts. So far I have not read where anyone is using a 180 or larger main jet. Most are 178 or smaller and seem to be working well.

Trying to do a little fine tuning, I conservatively dropped the mj to a 182. I ran the bike a 1/4 mile in 5th at high rpms and shut it down. Pushed it to my shop and checked the plug. To my surprise, the ceramic was bone white, indicating a lean condition.

Based on this test, I need to go back up to the stock 185 or higher. I just thought this was odd as I have not read any posts of riders using the stock mj.

Ride safe.

Terry

Are you using an aftermarket exhaust or stock exhaust?

To do the test properly you need to run the bike at FULL throttle, hit the kill switch and coast to a stop, then check plug reading. Looking at your post, I would assume Oklahoma is close to sea level and running a T-4 pipe, a 185 or maybe slightly bigger main wouldn't surprise me. Also how cold was it the day you did it? That could have some effect also.

To answer Mudman, the exhaust is a stock head pipe and Pro Circuit T-4 silencer.

I did the test just as you mentioned. This is my first four-stroke off-road bike so I was guessing that my old two-stroke procedure would work fine. Sounds like it is correct.

The temperature was a beautiful 58f and we are at about 1,200 ft.

Terry

I agree with ksp, you definatley want to go with a bigger main. You're better off a little rich than a little lean. I'd assume with the airbox mod and the pro circuit, you've increased the flow at both ends.

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Being that the ceramic was or is white,does not necesserally mean thats its a lean condition.
You need to read way down inside of the insulator to get an accurate reading. Check this out on how to read a plug.
http://www.dirtrider...tting+help+fast

Thanks for the link, I'll check it out.

Terry