Yong Heng, parts or alternative

Jump to latest Follow Reply
N

nvelkhunter

Member
Aug 13, 2015
160
5
Nevada, United States
Decided to change the oil in my YH today. Figured I'd open up the crankcase to see how the crank parts are holding up. All looks good, however unit on has 5 or 6 hours total run time. Attempting to place the crank case cover back on I ran into an issue of the gasket membrane being a little too small. Line up membrane across the top and the bottom won't stay in its channel. Same left and right. After three failed attempts I've RTV the channel and the mating edge of the crankcase, centered the membrane as best as I could and bolted it down. Hope tomorrow's full cured testing results in no leaks.

Searched the web but could not find a replacement membrane. Any one have an idea where to buy one or recommendations on how to make one?

Picture of "membrane" on crankcase face plate, face plate facing down.

1558836936_13647725025ce9f6c807f196.18465431_Membrane.png

 
My method is to stretch the membrane in all direction and put it quickly in place before it shrinks back to the original size. The working time window is no more than 3 seconds. I managed to get it done after several attempts. There has got to be a better way to do it. I am asking the Yong Heng how they install it in the factory. 

edit : the Yong Heng people suggested to replace the membrane with a new one. The cost is 5 Chinese Yuan which is less than one US dollar. I am located in Hong Kong so I can get it from their on-line shop in China. I think Yong Heng has an official shop at Aliexpress as well, may be you can ask the seller there. They may be able to get it for you even if the parts is not listed. This is how Chinese do business. You need to talk to them.

I will never remove that membrane again unless it is absolutely necessary.
 
Upvote 0
curiosity killed the cat or this case the gasket, all I have is one word screaming at me it's why

there should be a form rule never, ever open up goods made in some other part of the world unless you can get the parts

ok what is this membrane, could it be just a sealant that the use at assembly and so it isn't a gasket at al

https://www.google.com/search?safe=off&rlz=1T4GUEA_enUS644US645&source=hp&ei=dPPpXIHTI7zB0PEPuKKt2AE&q=motorcycle+case+sealant&oq=motorcycle+case+sealent&gs_l=psy-ab.1.0.0i13.2463.11703..13606...0.0..0.95.1582.26......0....1..gws-wiz.....0..0j0i131j0i22i30j0i22i10i30j0i10.6Jxxt_YUqJ4

I any good luck
 
Upvote 0
If you really cant get the membrane at the end, you may consider not using it and use silicone sealant or gasket makers to seal up the gap. The downside I can imagine is that oil droplets stirred up by the connecting rod will go to the breather tube unhindered. This will result is more oil mist being sprayed out of the breather tube when the compressor is running. Not good for health. May be the original breather tube can be replaced with a better one to alleviate the problem.
 
Upvote 0
I believe I would cut one from an old inner tube (should be free from a tire shop). I am also sure sheet rubber is available from McMaster or MSC (probably even e-bay)!
Click to expand...

I am afraid that will be impossible as it is not a plain sheet but one having a ridge running along it's perimeter mating the groove on the crank case . To seal effectively , the ridge must go fully into the groove. This is difficult to achieve if the membrane has shrunk. 
 
Upvote 0
i dont know why it should be needed ? Stopping oil from splashing through the oil breather nozzle ?!?!
Click to expand...

Yes, I think that's the purpose. The membrane isolates the air just behind the cover and those in the space where oil is being violently stirred up by the connecting rod. Without this membrane, I believe a lot more oil droplets will come out from the breather nozzle and pollute the surrounding air you breath.

If your YH does not have it, it's either a very old version or it is used and the previous owner has removed it. 
 
Upvote 0
Well, that's just my theory but it makes sense to me. There has got to be a reason for it to be designed that way. Some members of this forum have reported seeing fine mist of oil coming out from the breather tube and presence of oil smell around the area where the compressor is running. Just to be on the safer side, I wrap kitchen paper around the breather tube of my Yong Heng to provide additional filtering. Doing so may be redundant but it's better to be safe than sorry. 

1558965135_15616400185cebeb8fad73e1.98597435_x.jpg

 
Upvote 0
I believe I would cut one from an old inner tube (should be free from a tire shop). I am also sure sheet rubber is available from McMaster or MSC (probably even e-bay)!
Click to expand...

I am afraid that will be impossible as it is not a plain sheet but one having a ridge running along it's perimeter mating the groove on the crank case . To seal effectively , the ridge must go fully into the groove. This is difficult to achieve if the membrane has shrunk.
Click to expand...

Or home depot has shower pan you could cut to size
 
Upvote 0
Well, that's just my theory but it makes sense to me. There has got to be a reason for it to be designed that way. Some members of this forum have reported seeing fine mist of oil coming out from the breather tube and presence of oil smell around the area where the compressor is running. Just to be on the safer side, I wrap kitchen paper around the breather tube of my Yong Heng to provide additional filtering. Doing so may be redundant but it's better to be safe than sorry. 

1558965135_15616400185cebeb8fad73e1.98597435_x.jpg
Click to expand...

Nothing wrong with being safe. Personally, I believe some blow-by is inevitable and would be a more likely cause of any misting than would membrane design. Could be totally wrong though.
 
Upvote 0
You must log in or register to reply here.
Top Bottom
Back
Home
Forums
Resources
Menu