There has been quite many reports on the top of the first-stage piston of Yong Heng cracking after some use. Although mine has been working fine for about a year, I decided to take this to the Yong Heng factory in China and see if they will do something about it. It turns out that they have been listening to you guys quietly and have made a strengthened version. The new version costs about 4 bucks shipped to Hong Kong. The package includes the piston with rings, retaining rings for the wrist pin and a pair of gasket for the first-stage cylinder.
left : old version, right : new version
The measured thickness of the top is 2.75 mm for the old version and 4.38 mm for the new one which represents a good 60% increase in thickness. They told me that all compressors coming out from the factory now are equipped with the new piston. If you guys need to replace the piston, make sure that the new version will be ordered.
left : old version right : new version, note the big difference in the thickness of the top
The most visible differences are on the inner side :
left : old version, right : new version
The measured thickness of the top is 2.75 mm for the old version and 4.38 mm for the new one which represents a good 60% increase in thickness. They told me that all compressors coming out from the factory now are equipped with the new piston. If you guys need to replace the piston, make sure that the new version will be ordered.
left : old version right : new version, note the big difference in the thickness of the top
The most visible differences are on the inner side :
