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Jay Gilling
Jay Gilling
Rabbit Creek, Alaska, USA
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Re: A65 OPRV question
Mark Z #787816 10/22/19 11:47 am
Joined: May 2013
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From my experience I find the piston resembles more like if it was attacked with sand paper and sanded in straight lines along the length of the piston. Bad enough in some cases to have worn flats on the piston.


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Re: A65 OPRV question
Mark Z #787855 10/22/19 6:42 pm
Joined: Jul 2012
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Hi

Just a thought. I wonder how many of the galled PRV's were fitted straight from the packet, with no lubricant pumped into them prior to installation! Or how many fitted straight from the packet and installed sat unused for a period before the engine was kicked-up!
Admittedly stainless of similar grades used for both body and piston do run a high risk of galling, although I'm not aware if SRM use two different grades of stainless for their bodies and pistons in their PRV's which would reduce the risk of galling.

My tuppence worth

John

Re: A65 OPRV question
Mark Z #787859 10/22/19 7:11 pm
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Although the triple's gear pump does not have the wildly varying pressure of a Triumph twin plunger, the pressure is still not constant. As each gear tooth pushes out the oil there is a pulse in the pressure which, when the pressure is above the OPRV setting, causes the piston to oscillate, besides the condition when the valve starts to open the release in pressure lets the valve close. You sometimes get this condition in your water faucet when slowly changing from closed to open or vice versa. This oscillation might be the cause of the piston galling (or is it Gauling?).

Re: A65 OPRV question
Mark Z #787867 10/22/19 8:28 pm
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The only metal that can be reliably used on both surfaces of a bearing or similar is cast iron. Otherwise both surfaces need to be dissimilar


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