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01 cr 250 surging

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I have a 2001 CR 250 that I just put a top end in and I took it out over the weekend. When I am riding and I come up to a stop it surged for a like 20 sec then idles down at runs fine any one got any ideas? Cleaned the carburetor last fall and had no gas in it all winter. Just put the bike back together only has about 2 hours on it. Thanks jimmy g :thumbsup:

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You may have an air leak. When the engine gets hot, the air leak starts.

Also, check you jetting and make sure the carb is clean, is the fuel old?

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i will look into an air leak that is what i was thinking. the fuel is fresh this year and as far as the jetting goes it is the same as it was last year and it was fine.

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i have a 2000 cr250, just good it alittle while back. when i got it, it was on the rich side 180 main and 48 pilot. i swap them to 172 main, 42 pilot and it ran good until i rode this little grass track and rode it hard, i think it was doing what you are talking about idle up when i stop or inbetween gears so i went back up to a 175 main, and a 45 pilot. now it's jetted clean and you can run it hard as you wany to and it does not idle up. I guessing you just need to bump up your main or your pilot. go 1 or 2 sizes on pilot and try it.

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Sounds like an air leak. I just had this problem last month. My brand new head gasket blew out and was sucking air.

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could be your throttle cable as well mine did that before look in the manuel and run it the same exact way any different and it will surge esp when you turn to the right

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You have to do some troubleshooting

1. Air leak

2. Throttle Cable issue

3. Carb/Jets are dirty or float level is off.

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i bet its an air leak, ither somewhere in your intake boot,reeds,crank seal or posibly even a crank case gasket.

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i will take a look and see if i can find an air leack in it i dont think that it is a jetting problem i didnt do anything to it but put a new piston in it. thanks guys

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I always had problems with the base gasket on my 01. It seems like I had to use permatex or yamabond to keep that thing in place. My 01 cr500 had the same problem too.

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Can you explain how a float level could make it lean? I eyed mine and made the overflow stop and the idle is perfect. Could the float still be lean?

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i didnt do anything to it but put a new piston in it

That's why myself and most others are guessing an air leak. I wounldn't ride it anymore until it's fixed, since an air leak could make it run very lean. Since you just replaced the top end, obviously any gaskets you replaced during that are prime suspects. Air leaks are kind of nicer problems, since the solution is generally pretty straight-forward. :thumbsup:

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thanks guys i have been out of town for a couple of days but i took it apart last night and changed the base gasket and sealed it with some permatex to seal it it ran just fine last night rode it around the house for a min we are going to ride this weekend so we will see thanks again

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I hope you got it fixed but if it does it again when you go riding turn in the air screw and see if it helps. Good luck.

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i changed the base gasket and sealed it with permatex still has the problem going to pull the carb apart and clean it tonight if that doesnt to it i think i am going to take the power valve out and clean it. we will see hope this works.

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As i said before sounds just alittle lean on the pilot or main. try turning the air screw in or bumping the pilot up 1 size and the main up 1 size. It's getting hot while you are runing it and leaning out. Cleaning the carb may fix it, if one of the jets a clogged that would cause it to run lean anget hot. A new top could have the compression higher and your old jetting is too lean for new topend. Clean the carb first, then if it still does it adjust you jets richer. Check the coolant, make sure it is not low. Good luck.

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ok so i this is where we are at i took the top end off the bike and went through the power valve and found that the pins that hold it all together are bent to shit. so i am thinking that it is what do you guys think. and also i said that i didnt change anything on the bike when i put the top end in but i did put a new silencer on it. It is a USFA one insted of the pro circuit.

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