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Old 05-27-2012, 11:10 AM
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Join Date: May 2012
Last Online: 05-27-2012 11:11 AM
Location: High TimesPA
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Default 02 yz250f HELP


The last time i rode the bike it ran good all day till i was on my way home. i pulled out onto a road and started getting on it pretty good and it started to feel like the chain was jumping (i noticed it a few other times before this). i backed off and just rode it easy for about another 2 miles then it started to do it again then the bike just shut off and it hasn't ran sense then. I'm prepared to tear the motor down but want to get some advice first.
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Old 07-06-2012, 08:46 AM
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Join Date: Jun 2012
Last Online: 10-17-2012 10:15 AM
Location: Western NC
Posts: 45

With your bike on the stand, in neutral, spin the rear wheel and watch the countershaft sprocket... is it warping or moving unnaturally when it turns??
You said the bike hasn't run since, so it won't start at all? Can you cycle through the gears with the bike off?

If the trans seems fine, and feels fine, check your top end. You may have broken the timing chain, or dropped a valve. Just take your bike apart (gas tank, seat, etc), and remove the valve cover, and look at the head. Now cycle the engine with the kickstarter slowly, watch the cam timing chain turn the cams and see the cams depress the valves. If everything looks good there, you may as well check to see if your valves need adjustment, since you are right there anyways... check your plug too.
If that's all good, remove your carb and clean it, and check to make sure everything works correctly there...
Post back and we'll see if we can get this figured out!
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Old 07-06-2012, 08:59 AM
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Default OK

OK, don't over look the obvious of worn drive gears or chain and that the chain is adjusted properly.
The other advise already posted can help with the starting issue.

Paw Paw
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Old 09-28-2012, 05:46 PM
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Join Date: Jul 2008
Last Online: 09-29-2012 10:23 AM
Location: Pennsylvania
Posts: 5

Check the clutch too
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