2003 cr 125 carb swap help. Jetting

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12/30/2018 3:55 PM

Hi all. Just got myself an 03 cr 125. Got it for a bargain as something is wrong. Firstly it totally spat oil out the exhaust, previous owner then replaced the crank case seal and took it out on the track where it locked up. Previous owner seems to think it locked up due to oil being in the Photocrank?New top end then hasn't been ridden since. So now I've got it and noticed it has a keihin pwk on it. Not the standard mikuni. So now I'm in doubts, is the jetting out so much it caused it to seize? My main question is, is the standard jetting specs the same for the keihin as it is for the mikuni? I don't have space to ride it to test so getting base to start with for now would help until I get it out. Any help much appreciated. Thanks


12/30/2018 11:13 PM

Mikuni v. Keihin are completely different specs.

After fixing that front brake line, I'd start here:


12/31/2018 1:36 AM

2006 cr 125, stock cylinder/head with 0.9 squish
Vforce reeds
Pro circuit exhaust.
Base jetting in courtesy of digger.
38mm pwk air striker, can't remember slide.



12/31/2018 3:28 AM

Thanks for the reply chaps. Aside the carb issues the bike needs a lot of other work. Unfortunately I'm completely new to carb settings. I don't know the ins and outs of jets, if it's rich or lean. The most carb work I've done is fitted a jd get kit to my ktm, and even then I had help with that. If need be the bike will be stripped and rebuilt. Just trying to do a little troubleshooting. Will get the carb off today and have a look at how it's set up.


12/31/2018 8:58 AM

Got the carb off today and had a look at the jetting. Forgot to check the air screw. It is as follows
Needle, 3rd clip
Pilot, 55
Main, 165
Slide, 5
Keihin pwk s63a1haa

Judging by the above article its not the correct jetting. Is this right?