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yz125 jetting question

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I have a 06 125.

I ride at 4500-7000 ft.

Main jet 400, stock needle clip at 2 groove from top. 35 pilot, air screw 2.5.

The engine bogs and seems like it wants to die when the throttle is first opened right off idle. It was defiantly too rich with the stock pilot jet and seemed rich with the 37.5. I dont remember if it had the bog or not. I sprayed wd40 around the stater to look for air leak and the engine idle did not change when I did it. Just wondering if anyone has jetting suggestions? I really dont know if it is lean or rich. it does seem like it is lacking some low end tork.

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Do you still have the second needle that came with the bike?  It acts as a half-step change in clip position on the needle.  I ride at a different elevation that you, but I did find that half step made a big difference for woods riding.  With the stock needle I was getting too much spooge, or if I moved the clip, a lean bog when I whacked the throttle.  The half-step needle cleaned up the spooge and eliminated the lean bog.  It's not perfect, but very rideable.  

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I only have one needle. I bought the bike used. I was thinking the off idle bog was the pilot. I guess it could be the needle or clip. Im really not sure if I am lean or rich. I guess I need to play with it more and see

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