YZ250F Carburation.

For those who have the bike,or who have spent some time on it. How is the bike breathing for you. Did you need to make any adjustments, big or small to the flat CR? The reason I ask is my 250F is rough when you try to bang the throttle. I believe it is loading up on me. I did change my riding style the second time I rode it, higher up in the rpm's.

This is only my second four stroke I've ever owned. So I may be riding it like a two stroke when I shouldn't be. For the most part it runs supurbly. But every now and then when I roll to a stop with the clutch in, it dies. Not every time. Maybe one out of every ten stops.

I just got the bike, so this question pertains to how your bike ran right out of the box. Was it good right away, or did you change some things. Leak jet, pilot screw/jet, main jet, clip etc.

Obviously I know there are a lot of different places to live in the US all of which have different altitude and climate. But your input would be appreciated nevertheless.

I hope to get more time with it this weekend, maybe look at the plug, try some race gas, jets, etc.

BTW, this is my first post here.



Welcome to Thumpertalk! I doubt is has too much to do with your riding style. A friend just bought a 250F and is experiencing some of the same issues with his. He showed me a sheet from White Brothers that explained how to set up the carb. You may want to contact White Brothers or look for their website - I don't know what it is. Good luck with the new bike! Get mine in January...


I have about 4 hours on my 250F and have the same problem. I removed the plug and just as I thought it was black as could be with a very small white spot in the middle of the electrode. I think the jetting is fine but the needle is too high (IE one clip position too low). I have not changed the position of the needle yet (too wet to test), but plan to soon. I did go too 1 3/4 turns out on the "air" screw, it helped a little. Keep in mind that I'm not very good at jetting issues and you should get a second and third opinion. Not much to go on but I hope it helps.



'98 YZ400F

'01 YZ250F

'98 CBR600F3

That screw is a "FUEL" screw. Turning it out richens your jetting.

What is your jetting stock? (as the manual shows) Pilot jet, pilot (fuel) screw turns, needle number, clip, and main jet.

Post the specs and we can help you.


Main 175

Needle OBELP-4

Pilot 42

And a bunch of other jets...

It seems odd that the bike is rich especially

in light of the article in Cycle News. They

state that the bike might be lean.Also there

another post a few weeks ago stating that the

biek might be lean.

If you do get the jetting worked pls pass it

along since I'ss probably run into the same thing, I'm picking up the beast this afternoon!!

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