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jetting a cr125

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hey guys help me out here im a 4 stroke guy and got draged into rebuilding a freinds 125.

Here is what i have stock cylinder wisco piston. pro circut platnuim pipe. factory sound muffler.

i live at 3000 feet and ride up to 5000.

i am looking for a base line start and i can go from there.

any help would be great.

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guys any help at all would be great even a stock jetting would be good. i dont know what it is.

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I’m not sure about the temperature that you were trying to target? So I have posted a chart that should be of help. I used a 370 main, stock 6BEG20-69 needle with the clip in the 2nd clip position from the top, and a 37.5 pilot for 70 degrees and 0’ elevation. Start with you airscrew at 1-1/2 out from fully seated and you will be within 3/8 of a turn + or – from the ideal setting. All you need to do is find the temp and elevation combo for your current riding conditions and adjust your main, clip position, and pilot jet accordingly. I hope this helps you out. :)

2001CR125Jetting.jpg

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Holy thread revival batman! Well guys it has been a year since i did the work on this bike a due lack of interest and money it just came time to finish up the jetting work. I have to say thank you to Vetmx your chart was a great help i should become a sticky on the honda forum.

Final jetting with pro circuit pipe and silencer.

main 360

pilot 37.5

needle 1st clip

i am thinking about grabbing a step leaner needle to give me some wiggle room

I did a plug test today and the plug came out that perfect shade of brown we all look for in a engine.

This little 125 flat out screams i would say it will give my yz250f a run for its money up to 60 mph.

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