2003 yz250 carburetor problem!!

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12/10/2018 1:53 AM

Hello all!! Have a huge problem with float valve jet#70. While rebuilding the keihin carb I found that the float valve jet wouldn't come out. I couldn't loosen or tighten it, like it is stripped. Any suggestions on how to remove it and also how to remove the valve jet seat would be greatly appreciated!!! Thanks so much for taking the time to help.Photo


12/10/2018 3:10 AM

My first approach would be to tap some threads into there and make a slide hammer to pull it out. Ive never had to remove one, so there might be another way. Thats just first thing that comes to mind. Those seats are pressed in pretty good.


12/10/2018 7:13 AM

Makes no sense the plunger should just fall out. Did the bike sit for a very long time? Could be the old gas goo has hardened.
I would squirt some good carb cleaner in the fuel hose fitting and let it sit in there for 8-12 hours. Try blowing air down the fuel fitting so you are pushing it out.

I bought a carb cleaner from harbor freight maybe get one and let it do its thing over night?


12/10/2018 9:39 AM

Thanks very much for the information. I'll try the carb cleaner, although I don't understand the part where the "plunger show just fall out"? The jet is threaded and the seat appears to be pressed in as kb228 suggests.


12/10/2018 3:49 PM

The plunger is not falling out and this happened because it got corroded in there, likely from sitting too long with stale gas in it.

You will have to get it out of there somehow. Soaking in some penetrant oil might help.

Yes, the seat is pressed in the body of the carb. Once you get the plunger out of the seat, you will have to clean up the seat if it is grooved or corroded. Some guys have had luck polishing the inside of the seat carefully with brasso and q-tips.


Powerband in every gear !

12/10/2018 4:36 PM

Thank you I'm going to soak it in penetrating oil over night and have a successful report tomorrow!! Gotta look at the positive... Or else I'll bounce it off the floor!!! Seriously though, I appreciate all the help, it's my sons best friends bike!! He traded his 93 125 for it and he'll come out on top even though we have to replace the top and bottom and rebuild the carb!! Good project for them to learn on.


12/10/2018 6:31 PM

That is not a threaded in jet. It is the float needle and it slides in and out with the float to let gas flow into the float bowl and cuts the flow off when it seats in.

Crazy as this sounds after all the carb cleaner has avaporated heat it with a lighter. If you see a puff that should be it opening some and it might slide out.

After you get the needle out clean the seat with carb cleaner and a Q tip. Turn the Q tip to clean it.