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quickie dianosis

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ok....I haven't worked on a 50 in a long time. My son is having issues with his ALL STOCK crf50. Help me out. It would only run half choaked. So I pulled the carb and airbox apart, and cleaned thoroughly. Now it will idle fine with unchoaked. But if I thouch the throttle, it dies. If I half-choak it, I can throttle it fine. Diagnosis?

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Sounds like an air leak in the intake. At half choke it is restricting the amount of air coming in through your filter which balances out the air it is pulling from a damaged gasket.

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Good thought. After your suggestion, I removed the intake and checked both gaskets. They "look" fine. The o ring is good on the upper gasket too. And I don't see any cracks in the intake. Here's a video of whats happening.....

th_crf50.jpg

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is it warm? ours did that before it was warm. but it also stopped doing that after we replaced the top end. check the compression.

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hot/cold doesn't seem to matter. He can run it around for 30 minutes and I still can't turn off the choke or.....well, you see the video.

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although gaskets and o rings look good, some will still leak. spray some carb cleaner around the intake and anywhere you think it might be leaking.

however, the leak may be a small issue, i am thinking the carb is the bigger issue. i would pull it apart completely and reassemble to manual specs. this will get you inthe ball park. if it is still running bad, i would test the electrical.

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If you have to run the bike with the choke on, it is due to the pilot jet passageway being clogged. The best way to clean the carb is to have it dipped in an ultrasonic dip tank, to break up and dissolve the gummy residue that is in the passageways.

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i put mine in a gallon of the carb cleaner from autozone and it took the finish off of it, so i would not recommend doing that just from my experience.

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If you have to run the bike with the choke on, it is due to the pilot jet passageway being clogged. The best way to clean the carb is to have it dipped in an ultrasonic dip tank, to break up and dissolve the gummy residue that is in the passageways.

Does that wash with whats happening? I mean, the fact that it idles fine with the choke off? I had the carb on my work bench in pieces. Cleaned as well as I could with carb cleaner and rags.

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I've pulled the carb apart again just to triple check it. Cleaner and a toothbrush at work....

IMG00638-20100317-1259.jpg

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Well....I don't know what did it. But she's running correct now. Only thing I did different in this cleaning was pull out the main and pilot for a hard toothbrush scrub. Didn't look like I made a difference. I was shocked that the bike took right off after installation.

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Please tell me what you did, mine is doing the exact same thing and I have taken it apart 3 times!!

Thanks

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