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02 YZ250F Jetting Help

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Ok I finally got my pilot circuit/hanging idle issue worked out. I'm now trying to tackle some bog from 1/8-1/4 throttle.

40 Pilot

100 Leak

4th clip stock needle

178 main

Full Pro Circuit t-4 exhaust

Before I get suggestions to buy anything ie a JD Kit, I'd like to try working with what I got. I'm looking for some suggestions on how to tune in order to get rid of the bog. Should I move the clip on needle? Which direction? Do I need a different main jet or leak? Any help would be greatly appreciated.

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Thanks William. I'll give the O-Ring Mod a try. I moved the needle clip from the fourth groove to the fifth and that seemed to help a bit.

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Needle clip position only affects operation between 1/4 and just below WOT. Between idle and 1/4 throttle, it is the AP and in some cases, the straight diameter of the needle (which can only be changed by a needle swap).

With the oring mod and a smaller leak jet (I suggest first trying a 60) your bog should go away.

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