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The TTR250 FAQ web pages -> TTR250 -> Projects and restorations -> Valve clearance issue
Post Info TOPIC: Valve clearance issue
dlee22


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Valve clearance issue
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Hi there,

Love my ttr, it's done great however my valve clearances are pain. I cant get exhaust valve shims thin enough for the proper gap now, does this mean the valves have warn to the point where they need replacing? Am I right in thinking the top of the valve shaft has warn down and effectively got shorter?

 

I'm just trying the understand, and work a solution. The last time I checked them was at the start of a 15k trip so other than basic service maintenance I tried avoiding any engine work whilst away.

 

Any thoughts are very welcome

 

Thanks



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Daniel Lee
TTRfan


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I think it very unlikely the top of the valve stems will have worn.

What I think is more likely is that, over time the valve head wears, along with its seat, and it gradually sits into the head further thus reducing the clearance at t'other end.

Brian



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dlee22


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Ahh okay, in that case a pair of new valves will be needed then?

Can the seats be removed from the head and replaced?

Thanks

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Daniel Lee
TTRfan


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Get the head off and check all the valves and seats before spending any money.  If the valves have a definite ridge on their seat surface (or are pitted as I have seen occasionally) then get new ones. It is less likely that the seats will be worn as I think the valves are designed to be the sacrificial part.

If you have to buy new valves then you may be lucky and they will grind/lap in evenly. Otherwise the valve seats might need re-cutting, You don't really want to do that if it can be helped as it puts the stems up in the head a fraction....

Don't forget to fit new valve stem oil seals whilst you have the valves out!

Good luck - if you need help or advice just post up a message biggrin

There are a few guides that may help e.g. this one.

 



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