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The TTR250 FAQ web pages -> TTR250 -> Repairs and maintenance -> Dreaded clunk . Plus kickstart locking up engine .
Post Info TOPIC: Dreaded clunk . Plus kickstart locking up engine .
rdchair


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Dreaded clunk . Plus kickstart locking up engine .
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Hi all . Help please . 🙏 bike was running great trail riding at the weekend . Went to start to move up step in garden and it let out an awfull mechanical clunk . I tried to just turn over with kickstart and it was locked . Rocked bike and kick went down once then locked again . Stripped first cover off , all cogs in good condition . Starter spinning fine . 
Stripped sprag clutch and whilst there is signs of wear , it seemed good  enough to try again . The kickstart would still not go down unless I rocked the bike , then it would lock again even with the flywheel off . I decided to reassemble that side and look at the clutch side , again nothing untoward . I reassembled and tried to start . It turns over but would not start and after trying . The kick start Is again locked . Any clues ? 
 Bike is 04 13500 miles . Been ultra reliable with IMG_2886.jpeg regular oil changes . 



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Ttboof


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I've been reading and thinking all day not sure of what it may be . If the gears are out of the starter side it should turn ok if it's the sprag .

Hope you find the reason soon 

 



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mossproof


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As Les says, if the flywheel side is all removed and the engine still won't turn, the problem is not on that side.
I would check the cam chain sprockets - if the chain has jumped, the piston could be hitting the valves and locking up.
Pop the spark plug out and see if you can turn the engine using the clutch basket. Just rocking the clutch basket back and forward might show you where the jam is occurring.
Good luck!

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rdchair


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Cheers . Some have suggested a valve ? 



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Ttboof


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Agree would be next step 



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rdchair


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71926D47-447F-41EC-8CB0-4885533C8395.jpegUpdate . Looks like rear cam has jumped 2 teeth but everything looks good nick ?



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Jeff B


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Looks like your off by 1 tooth on the intake cam.



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-Jeff
mossproof


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Well readjust it and try it! You can't tell if a valve has bent by looking at the top, unless the cam clearances are unnaturally large, indicating a valve is not closing properly.
Turn it over by hand with plug out - don't spin it on the starter motor.
Glad you've found something anyway. Fingers crossed...

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rdchair


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YepnoIMG_3139.jpegIMG_3144.jpegIMG_3140.jpeg



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rdchair


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Looking for a cam chin and guides . Or do I need them ? Guides look ok ? Do they have a channel from new ? Cheers IMG_3144.jpegIMG_3145.jpegIMG_3146.jpegIMG_3147.jpeg



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mossproof


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Cam chain guides do have a groove in. What is the chain tensioner like? Wonder why it jumped a tooth. Combination of stretched chain and tensioner losing it's tension?
I would be looking for a pair of valves first - stuck open so probably bent from hitting the piston.

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Rossyboys


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Good luck with the fix, nice clear pictures to help everyone, pictures do say a thousand words in this case. Cheers

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rdchair


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So definately a new chain , new cables , guides as 1 looks cracked . Seals and gasket set . Also gone for a mechanical tensioner as that can be only reason chain jumped ? Also notice inlet manifold perished so new yam one on order . Are the guides easy to remove ?  



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rdchair


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So confirmed cracked guides . who are the go to people to remove and refit ? 



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TTRfan


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Always best to go local if you can. Ask around your local motorcycle buddies. They are sure to have a favourite engineer who works on their bikes wink



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