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Darrell
 Post subject: Valve Resession
PostPosted: Mon May 16, 2016 8:38 pm 
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Do 940 heads suffer from valve recession when running ulp without a fuel additive? my no 2 exhaust valve stem has severely worn down maybe 1/8 in all the others are fine and clearance settings standard.

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simon k
 Post subject: Re: Valve Resession
PostPosted: Mon May 16, 2016 8:47 pm 
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yes they do... but you might have one soft valve stem too?

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Darrell
 Post subject: Re: Valve Resession
PostPosted: Mon May 16, 2016 8:49 pm 
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That's what I was thinking Simon seeing as the others don't appear to have the same issue.

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drmini in aust
 Post subject: Re: Valve Resession
PostPosted: Mon May 16, 2016 9:36 pm 
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Is the valve sunk into the head, or is the valve stem looking lower when assembled? If the latter, perhaps it has a mk1 exhaust valve there (are 2mm shorter) and 3x oversized 12G940 exhausts.

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Tim I
 Post subject: Re: Valve Resession
PostPosted: Mon May 16, 2016 11:38 pm 
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Valve seat recession will close up your clearances, not make them larger.

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9YaTaH
 Post subject: Re: Valve Resession
PostPosted: Tue May 17, 2016 8:00 am 
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simon k wrote:
yes they do... but you might have one soft valve stem too?


or poor oiling to the upperworks? hows your oil pump?

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Darrell
 Post subject: Re: Valve Resession
PostPosted: Tue May 17, 2016 9:10 am 
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Stem is definitely worn, oil pressure is fine, will pull the head off and take a look only done around 10000 ml since rebuild, just seems odd that its only one valve. Thanks for the input guys.

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simon k
 Post subject: Re: Valve Resession
PostPosted: Tue May 17, 2016 11:23 am 
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Darrell wrote:
Stem is definitely worn, oil pressure is fine, will pull the head off and take a look only done around 10000 ml since rebuild, just seems odd that its only one valve. Thanks for the input guys.


sounds like one soft valve... the rebuilder or a previous owner might have bought a cheapie to replace a damaged one. If you run a file against the side of the stem tip you'll be able to to tell without taking the head off

limited experience talking, but the best value valves I've come across I bought from minis plus - the online store is in transition, but these are the inlet version... http://www.minisplus.com.au/old-shop/pr ... d-race-ser

send an email to see if he still has the exhaust version

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Darrell
 Post subject: Re: Valve Resession
PostPosted: Tue May 17, 2016 6:24 pm 
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Thanks Simon have run the file over the stem and yes its definitely soft had a burr on one side where the rocker wasn't making contact.

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