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98' YZ 125 jetting

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Question,

I got a 98' YZ 125 all stock motor. I run the bike in various temperatures throughout the summer months (1500' elev.). My question is when should I be swapping out my main jet.

Stock jetting in right now:

350:main 45:pilot 6BEF16-69:needle 4th:clip from bottom 2:air screw turns.

Throughout the summer I can run in temperatures ranging from 50's to 90's and I have never changed my jetting, only adjusted the air screw. I'm not worried about running the bike rich when its warm out, but I am concerned with running the bike lean when it gets cold out.

Should I be swapping that 350 main out for a 360 or 370 when it gets down in the 50's or do I have no worries?

This may seem like a stupid question but I'm too lazy to figure out the jetting myself and just want to know if someone else has already figured out a general rule. 20 degree drop from 70 raise 5 numbers on main, etc.

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also, nother question.

are boyesen super stock reeds good? put them in last night and wondering how they perform. If no one responds I let you know monday, Riding MX sunday at indoor track.

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i had a 98 yz125 and to be honest i never messed with the jetting on that bike. Had it for 3 years with plenty of mods, never changed jetting winter or summer. Whenever i pulled the top end they always looked great, never any lean problems.

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lean needle out two clips and jet from there.Not my experiment is what was suggested by MXA in 1998 and it really did make a difference.

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hmmm...I think I will pass on leaning the needle circuit but thanks for the idea. I think what I am going to do is just go up one size on the main when it starts dipping down around the 50's. Thanks for the help though

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you do what ever you want but i am right even pro circuit leaned it out check out there jetting specs for the 98 on there website.

YZ125 350 45 6BEF16-69 4TH 2

Pro Circuit STK STK STK 2ND 1 1/2

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I am going to have to correct your thinking there.

Stock clip position is 4th from the bottom. When you throw a pro circuit pipe on they recommend to run clip position 2nd from the bottom. This will raise your needle making the bike run richer.

Thanks though for the info. Anyone else got some general guidlines to follow?

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Have fun jetting because obviously you know what you are doing.Everone(except you) counts from the top of the needle when jetting. Each to his own though. CLOWN!!!

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