CRF250R help

Quad41
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Mims, FL US
Quad41
Edited Date/Time 1/27/2012 3:05am
So if anyone might relatively know what could be the problem here that would help me out greatly... I have an 05 crf250 and it had valve issues like every other stock 250r out there so I brought it to a mechanic (proven to be good, been bringing my bikes to him for years) and had him replace the intake valves, replace the water pump impeller and install a new piston that i believe was a little higher compression then stock but cant remember exactly what it was. and I had installed a white bros full exhaust.... Now I went to take the bike out some time later (still not even broken in yet) and the bike doesn't want to run when it gets hot. It'll start up on the first or second kick, idle good, no backfiring or anything, ride it up and down the street a few times and then bogs out as soon as it gets hot, almost like it runs out of gas. but ill let it cool down and then it will start right back up first kick again. I'm not sure if its valve clearance issues or carb or what?!?!

If you have had this problem let me know..
-Thanks
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mxtech1
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mxtech1 11/4/2011 11:13am
11/4/2011 11:13am Edited Date/Time 11/4/2011 11:14am
It probably wouldn't start right if the valves were too tight. Did the mechanic cut new valve seats on the valves that were replaced?

The issues are kind of baffling me because they are conflicting. If the bike ran poorly from the time you started it, I would say it's carb issues. But when it runs good at first and then starts bogging as it gets some heat built up...im not sure. I need some more information.

Does it completely die when this happens? describe the bog...is it at all throttle positions?

I think your first check is to clean the carb jets, new spark plug, and fresh gas.
lumpy790
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lumpy790 11/4/2011 1:58pm
11/4/2011 1:58pm
sounds electrical.....stator probably taking a poop.
motofab36
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motofab36 11/4/2011 2:31pm
11/4/2011 2:31pm
lumpy790 wrote:
sounds electrical.....stator probably taking a poop.
My guess also
Quad41
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Quad41 11/4/2011 2:53pm
11/4/2011 2:53pm Edited Date/Time 11/4/2011 2:58pm
Well I just pulled the bike out of the garage and dusted it off to see if i couldn't help you understand better... I swear it idled fine last time I took it out but anyways, plug was fine but i wire brushed it anyways, took out the jet and blew it out with the air compressor (#160 jet sounds small to me but idk) and used fresh 93 gas. Here's a go pro video... seems like all carb issue now but I swear it ran fine until it got hot before.

and i never even thought of the stator.. i bet thats what it is, i'll have to look into it later.. anyways here's a vid of the bike today.

The Shop

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ianhendry46
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ianhendry46 11/5/2011 7:24am
11/5/2011 7:24am
My friends bike did this, and since yuou put a new pipe on, its more than likely the same thing. The jetting and the fuel screw need to be adjusted. from the way you described it, im almost positive thats what it is, but then again i could be wrong. Hope this helps!
Quad41
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Quad41 11/5/2011 8:49am
11/5/2011 8:49am
Ok, i'm gonna try that gonna go pick up a few main jets hopefully it'll solve my issue... otherwise maybe replacing the cdi box will be step 2 if this doesn't work.

thanks for the help so far!
MOTODAD422
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MOTODAD422 11/5/2011 11:20am
11/5/2011 11:20am
Check the stator before replacing the cdi box. If it tests good leave it hooked up to the ohm meter and put a hair drier to it,some of them test good until they heat up.
Quad41
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Quad41 11/5/2011 4:28pm
11/5/2011 4:28pm
update... went to the local bike shop and picked up some main jets.. got a 165, 168, 170 and 172... ended up with the 168 but still bogs pretty bad when the choke is off and is kinda hard to start when its hot. I took an updated video, its real responsive when the choke is on and idles good..

http://www.youtube.com/my_videos_edit?video_id=ray1Re8mdZI&ns=1
Quad41
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Quad41 11/5/2011 4:29pm
11/5/2011 4:29pm Edited Date/Time 11/5/2011 4:30pm
i also adjusted the air fuel screw slightly, but it runs like crap on the bottom end and if I lower the idle it stalls.
xnationalwrench 11/5/2011 7:44pm
11/5/2011 7:44pm
Have you checked the slow speed jet (pilot jet)? If the bike has sat any time and especially if you use pump gas it can clog up pretty easy.
Quad41
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Quad41 11/5/2011 7:54pm
11/5/2011 7:54pm
I haven't. I don't know much about carbs, just some basics... can I clean it without taking the carb off the bike?
xnationalwrench 11/7/2011 4:23am
11/7/2011 4:23am
Quad41 wrote:
I haven't. I don't know much about carbs, just some basics... can I clean it without taking the carb off the bike?
it is possible remove the float bowl and this jet is right along of the main jet. It has some side ports but you want to be able to hold it up like a telescope and see thru it.
motofab36
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motofab36 11/7/2011 6:21am
11/7/2011 6:21am
The main jet has little to do with the symptoms you have. Clean or replace the pilot jet.

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