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The TTR250 FAQ web pages -> TTR250 -> Repairs and maintenance -> no compresion please help
Post Info TOPIC: no compresion please help
Aidan


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Ok so I have no idea what to do. I tried to start my bike and the timing chain jumped. So after disassembling it, fixing the timing chain and fixing the stupid timing chain tensioner. I have no compression.

I have rebuilt the engine (new piston, rings act) no more than 4 hours riding time ago. It’s barely worn in yet. I have double and triple checked my timing is correct. The piston is rising and falling with the engine as it kicks over. 

 

However no bloody compression

If anyone has any ideas please help. I’ve only just put the bike back together after having to rebuild the clutch (which I haven’t even ridden with yet).

Any help would be awesome

thanks aidan



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TTRfan


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Most likely a bent valve from the timing chain slip cry



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tracker


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Timing chain jumped with me,the woodruff key that locates the generator had sheared!

Don't know if the key shearing caused the chain to jump or the other way round.If its the key the Yam one is exspensive,so i made one,not diffucult just patience needed.



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Lin


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Bent valves. Confirm by removing the top cam cover and looking for increased valve clearance on either intake or exhaust side.

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Aidan


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Iv striped the top end apart and wow iv never seen valves bent that bad. Il take a photo an upload it but my exhaust valves are destroyed.

Piston looks fine though. As well as the intake valves. I blame an old timing chain and tensioner for the chain jump as the sprockets look fine but the chain is pretty worn.
Pity coz I had my first enduro race this weekend and was really looking forward to it.

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Aidan


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well here it is. as you can see light is coming straight through from the exhaust port

photo.JPG



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Cubber


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Oops! confuse

A bit of weekend work, methinks, Aidan. cry

There is plenty of advice on Brian's help page regarding cylinder head work.

http://www.ttr250.com/Removing_Cylinder_Head/TTR_head_removal.htm

Don't rush it - be methodical and check EVERYTHING - get it right. wink

Martyn



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TTRfan


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Lin wrote:

Bent valves. Confirm by removing the top cam cover and looking for increased valve clearance on either intake or exhaust side.

Sorry to have guessed correctly - that is an expensive repair cry

If MotoWard or Fowlers don't have them in stock for immediate despatch then PM me if you want the valves and cam chain put in 1st Class post today. I don't normally sell the new spares I keep for my own use but you sound desperate and this would give you a chance to get the TTR back together quickly. Gasket set also available if needed.

Brian



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Aidan


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Thank so much for the offer. Really kind of you. Iv already got on it and ordered parts and the head is already in the shop getting repaired. And yes I am pretty desperate, lol. But s$&@ just happens sometimes. But will keep updated on the status

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