YZ250 Bogs on Rev

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7/9/2018 5:50 PM

So I have been going through carb issues ever since my bike got fully rebuilt. The pilot jet was too small and causing it to surge at elevation, so I went one up on the jet and it solved that. Now it wants to bog down when you rev it out. Like when the bike is cold, ill let it sit for a minute or two and then give it a few cracks of the throttle and it bogs down.

Would going up on my main jet fix it? The main jet has no markings at all on it. Pilot is now a 58 coming from a 52 before. The A/F screw is 1 1/2 turns in. Bike idles kind of weird too I notice while riding it up at elevation.

Any suggestions would help. Wanting to get this fixed and running good before this weekend.

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7/9/2018 5:51 PM
Edited Date/Time: 7/9/2018 5:52 PM

Are the exhaust valves working?
Have you checked the float height?

Paw Paw

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7/9/2018 6:02 PM

Paw Paw 271 wrote:

Are the exhaust valves working?
Have you checked the float height?

Paw Paw

They are. Bike didnt do the bogging before changing the pilot to bigger. And the float height is where it is even with the carb when tilted at an angle.

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7/9/2018 6:54 PM

What year is the bike?

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10' 200 XC-w
96' XR600r

7/9/2018 6:55 PM

250F?
Check/adjust accelerator pump. Worked for me.

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7/9/2018 6:58 PM

Hcallz5 wrote:

What year is the bike?

10’ YZ250

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7/10/2018 5:39 AM
Edited Date/Time: 7/10/2018 5:41 AM

You have a mechanical issue, or more specifically an air leak somewhere. Under no normal circumstance should a YZ250 use a 58 pilot jet. I don't even know what needle I would use that would require a 58 pilot jet.If you're using the stock N3xx series needle you should be right around a 48 pilot jet.

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7/10/2018 8:03 AM

digger wrote:

You have a mechanical issue, or more specifically an air leak somewhere. Under no normal circumstance should a YZ250 use a 58 ...more

Checked for air leaks. Ive been through everything i can possibly think of. I had the 52 pilot in the bike around the house, it would not surge. I rode the complete crap out of it, wouldnt do it once. Take it up in the mountains and it would do it everytime. I went up on the pilot and it quit doing it. Ran great this weekend up in the mountains. But now revving it out it wants to bog out, not like it wants to quit but just sounds like crap. Im literally at a brick wall with this because every since i got this bike rebuilt completely it has been nothing but issues....

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7/10/2018 8:36 AM

You should not be going richer for mountain riding as the air is thinner and thus requires a leaner jetting which is just the opposite of what you are indicating.
Air leak, bad crank seal or crank bearing ( not allowing the crank to run true and thus cause it to loose the seal effect of the crank seal) are all areas of concern.

Paw Paw

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7/11/2018 6:05 PM

Check to see if your powervalve is completely closing. Pull the pipe and the right linkage cover off. At rest, the hole to use the pin in to disassemble should line up with a hold in the cylinder. If it does not, you may have skipped a tooth on the powervalve mechanism or have a bent arm.

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