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Jetting-2005 YZ125 suggestions

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I just picked up a used 05 YZ125. The motor is stock and it has an FMF works pipe and silencer. Jetting is stock as well. I am in Idaho at approx 2800 feet in elevation. The bike seems rich off the bottom and acts like if you don't keep the revs up it will foul the plug. Top end is pretty fresh. Running synthetic oil mixed at 32 to 1.

My thought is to drop the Pilot from the stock 40 to either a 37.5 or 35.

Burned, any suggestions? If you keep it pegged it runs fine but it will be used on trails as well and I want to dial in the low speed jetting. Main is a stock 410 and needle in stock clip position.

Thanks Dve

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my bike is the same way . going small on the ploit jet did not fix mine . the guys at yamaha , just's looks at you . he said La Vegas & So cal tracks are working good with the stocks jets . I think not . I am trying new needls next I will let you know .

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my buddy has an 05 went to 35 pilot stock main one clip leaner (one closer to the top of needle ) 2200ft bike runs awsome.

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well today we installed pilot 45, changed the needle one leaner & installed clip in stock #4 the bike runs good off the bottem no bog somewhat a longer power band . the bottem end is there when you need it. the plug looks just a little lean at mid range but the top end will hold together maybe one up on the main.,maybe

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Thanks all for the suggestions. I had not thought of leaning the needle as this richness is just at initial throttle opening, right off the bottom of the rpm range. I'll try the bike this weekend with the 37.5 in it and see how it runs. Did seem a little better just on a quick ride around the street. Just trying to avoid plug fouling when my boys ride it. Have to educate them on how to ride a 2 stroke since they have never ridden one.

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i had very good luck with a 5.0 slide still useing it here in cali its hot and the elevation at 2500ft .. jetting was a real problem before with the 4.0 slide

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