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Keihen Carb for 03 cr 125

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So, i've come to the conclusion that the mikuni carb on my cr 125 is complete trash. I've read a couple posts regarding the Keihen carb for peoples cr 250's and that it helped a lot. My cr has ran wrong from day one. Fouls plugs all the time, I've purchased larger jets and had it running nice and then "boom" fouled plug in the middle of no where. I'm running klotz at 40:1, should i be running closer to 50:1 ? It does seem like there is still too much oil in the mixture.

I was thinking about selling my bike and getting a same year yz125, but it seems like it will be difficult to sell my bike (too many two strokes on the market).

Should i try 50:1 or just got for the keihen carb? Is the carb swap even worth the money?

Also, I am running the BR9EG plug. Should i be running something else?

i've had this bike for 4 years and it's only ran good twice. I'm pretty sick of it.

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I'd stay at 32:1 for a 125. If the engine's healthy (crank seals, rings, etc.) and you're getting a lot of drool, you probably need to lean out the air screw, the slow jet, the needle position, or maybe all three. Unfortunately, I'm not familiar enough with 125 jetting to make a recommendation, but have you at least jetted according to the factory jetting chart for your conditions?

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Get the Keihin carb. What kind of riding do you do with it?? Makes a diff on what model/size of carb.

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the stock settings are horrible.

I think the main problem is that i added a boyseen rad valve setup onto the bike even before i had it fixed stock. The bike has run like crap even from day one.

I just changed the top end so thats not the problem.

I leaned out the pilot and main jets and the needle clip is in the middle position. I think i might try 40:1 and if that doesnt work I'll get the carb.

I usually ride trails at gorman. They're not billy goat trails, sometimes i'm wide open in 4th or 5th. I'm usually in 2nd or 3rd unless i'm going up hill after a corner.

can you advise me as to which carb and size i should get?

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First, never try to correct carburation problems with the pre-mix ratio!!!!

For trail riding, especially knarly trails where you spend a lot of time on the low-mid rpm range with short quick bursts of throttle....IMHO, on a 125, you cna't beat theold 36mm PJ. Now if you were going to be racing it or running it more wide open, spending more time in the upper rpm ranges, I'd say go with a 38/39mm PWK/M. The 36mm will give you higher flow velocities and hence a better signal at the low-mid rpm range. THe PJ also is better for the low-mid range and in 36mm will give you very good throttle response. they should also be very reasonably priced!

Start off with aboubt a 175 main, 52 pilot and a R1469n needle in the 2nd clip.

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i run 40:1 in my 02 with the mikuni stock jetting and a br8es and i have NEVER fouled a plug...i can even do rocky tight trail riding where it is just above idleing crawling over rocks and roots. it had the 8es in it from the previous owner

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Charlie, thanks for the advice. Everyone has been telling me i have too much oil at 32:1 i'm running klotz. some people told me to run 50:1 =/

Know any places where i can get the carbs? I have this one website bookmarked on my computer. Cant remember the website off the top of my head.

Mikedoug, I'm running a br9eg and it runs like crap. I think they changed some stuff on the '03's i believe. I love the way the bike handles, I just dont like the fouling i'm having and the abrupt power band. I rode a 04 yz and the power band is soooo smooth. Honda made a huge mistake by using the mikuni. I have no idea why they made the change.

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I was using Klots R50 32:1 in my sons 02 cr125 and Hes was fouling plugs about 4 on a 3 hour ride. Even at the track running wide open in third, fourth gear... I redone top end put in a yz needle and leaned out the pilot and main seems like 32.5 pilot and 160 main needle 3rd...kept fouling adjusted the carb float still not help ...Then my son said seems to be to much oil after 1 season of racing I'd change plugs on the start line... Today I finaly broke down and change the clutch side crank seal and I can not make it foul, cold start, ripping the throttle it never fould (yeeeehawww) I also went to yamalube. I started to buy the kehin carb I may yet but today I'm a happy man...

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dont really get what you mean...

So, you think it's the crank seal thats leaking? i really want to sell the bike and get a yz, but my father suggests i try the new carb first.

this bikes been a headache since day one... LEMONNNN!!!

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I think gorman is close to 4000 ft. elevation, hope you take this into account when you are jetting your bike. look in your manual it should show jetting changes for alitude.

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if your compression is low and you've done the topend and checked for cracked reeds and you still cant jet it correctly its the crank seal, about $20 and three hours install job

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