going to bore Vevor 2nd Stage to allow yong heng piston

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L

lodcomm

Member
Sep 12, 2018
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Connecticut
Hey Folks,

I have a Vevor pcp compressor with the completely flimsy (at best) second stage piston with the black plastic "caplike" seal that is prone to failure almost instantaneously. I am planning on boring out my second stage cylinder to allow it to accept and use the yong heng second stage piston (the one with the 4 black rings)

could one of you yong heng owners possibly mic the inner diameter of your yong heng second stage cylinder and post it or msg me with the dimension



Thanks most kindly



-t




 
The Hen and the Tuxings have the same high pressure pistons.Dim. run 347th.-370th.length2.5"- 2 7/16" you should,nt have to bore it? listen when your all done turn it over with the fan and make sure nothings binding? if its going beyond TDC you have to raise
1537136505_16780902275b9ed779762591.99581877_rings.JPG
1537136506_17528483945b9ed77a5a6f11.07863442_CIMG6927.JPG
the base plate.
 
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Well here is what I got measuring the Tuxing piston.

top end .383" or 9.75mm

shaft .361" or 9.19mm

seal .050 or 1.29mm

seal on piston with gap closed .39" or 9.9mm

How close I am I an not sure because of the tremors I have, but should be close.. But chinese manufacturing the tolerances can vary..

I can send the piston and seals to you if you would like..
 
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Thanks most kindly to everyone. 



Cosmic: I have a couple of the Hong Seng Replacement pistons (both the first and second stages)... What I really need is the inner diameter of the 2nd stage cylinder itself so I can bore it out to the proper diameter to accept the larger Hong seng second stage piston.

there is a bit too much difference in the 2nd stage piston diameter to get away with simply turning it down to match the OD of the Vevor, I would also have to re-groove the ring/seal seats and would have to modify (shorten) the ring gap on the plastic seals as they would be too large for the smaller piston. It will be much more effective and reliable to simply bore out the cylinder to match the ID of the hong seng.

thanks again!

-t


 
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There is about .020 difference. I ,m going two different ways. When I get back home I,m making a new brass plston with ring lands 

cut deeper to use Tuxing rings. I then will have too modify the rings to fit the groves. I,m also going to make some rings to fit the new

brass his piston. I really want to use the modified Tuxing rings. There cheap and can be bought a few places. I!m going to try both 

by new week. Boring is a option also but being away from my compressor without looking at the sleave I do not know if there is 

enough meat in the wall.

I will get back to you. FLy
 
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fly, cosmic - thanks tons for the good information.

Fly may be correct, there may not be enough meat is the second stage sleeve to bore it out - I am going to explore simply making a whole new sleeve - I will also try turning down the hong-seng second stage piston and cutting the ring lands a bit deeper - I suppose it would not be too problematic shaving a bit of the plastic off the ring/seal gaps.

thanks again to everyone for the input - hopefully we can come up with a relatively easy way to swap the piston with the hong-seng



-t


 
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What I did was turn a Tuxing high pressure brass piston to the same dia as a Vevor & deepened the ring lands so the Tuxing rings fit & cut the ring ends

down so they will compress with out binding. Now you can buy Tuxing rings & just cut the ends of those rings down. I did this for a friend. It fits find but tomorrow

I need to check the clearance of the piston to the head, before I send it back to him. 

Fly
 
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fly - great news - I have two of the hong seng pistons I will explore doing the same with - can you post the inch diameters of the outer piston & ring lands so I can attempt to do the same with one of mine.

I am also going to turn some PTFE replacement Vevor style piston ring/cups with solid walls and using a tapered cap screw to attach to see if I can increase the reliability of the stock piston.



-t


 
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