Sep 17, 2003
I'm just learning to jet my bike so any help would be nice. The problem is I have a bog just off idle. Which from what I read that it is problely running lean on the pilot jet. The bike is 91' cr125. To get the thing to idle at two turns out, I had to open the the idle screw what seemed like ten turns. On this carb the choke lever controls the idle.If I close the air screw the bike stalls. I went to get a larger pilot jet and the guy at the dealer told me I had it wrong that by opening the idle screw I was leaning it out and that by turning the air screw in was also leaning it out, so I must be running vary rich. He seem to think that I could go down a couple of sizes. It does not make sence to me, the idle screw is openning the choke is it not?Which would be making it richer. I'm already running 4 bellow factory 2 more seems like to much. The bike is stock. we ride mostly at about 4500 to 6000 feet.
I don't know what to do.
thank you for any help


Oct 4, 2003
The idle mixture raised the slid a little. Does not effect the air fuel mixture. DId you try the richer pilot jet? Have you tryed a leaner one? Id swap them out to see what way helps clear it up. Also on this year cr125 i would check the left side crank seal. They always seem to be leaking gas-oil mixture. Next time just tell the sales guy "ok. but ill try it anyway". unless you know he is really smart.

Big Daddy

Dec 10, 2002
Try a leaner pilot jet to get the idle up. I ran a 48 (stock 52) in my 98cr125 with the Keihin PJ36mm. You should also run a 1468 needle in the 3 or 4th slot. Part number 16012-KS6-004 This needle is in Eric Gorr book for 85-99 cr125's. It got rid of my bog.
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