Fuel puking out overflow line

[Lee R]

Originally Posted by Weldangrind

The tube in your friend's bike might not be sealing as well at the plug. If it doesn't seal, fuel will simply drip out as quickly as it is collected.

That's a good point, the plug in mine had almost fallen out when I reseated it. Maybe his was loose as well.

[detours]

I found a partial solution to fuel condensation in the catch tube. Turn the PCV separator upside down!

I was thinking about my last test and realized that if cutting a hole in the filter wall increased the fuel condensation, making the filter thicker might decrease it.

I don't know how to safely add filter media in there ... but since the filter inside is shaped like a cup (open at the top), I decided to invert the separator, so it opens toward the bottom - as shown in the pic. Fuel vapor now has to travel through the side and the 'top' of the filter, approximately doubling the filter media. This raises the vacuum pressure on the other side of the filter and reduces condensation.

Long story short, it cut the amount of fuel collected in half!

The engine used to generate just over an inch of fuel in the catch tube during my 30 minute commute. After drilling the hole, I collected about 2 inches during the same ride. Now, with my replacement separator inverted, I'm collecting only 1/2 inch of fuel during the same ride.

This is very encouraging. I suppose it's possible I'm losing enough pressure that fuel vapor is staying in the crankcase, but I doubt it. I think if Zongshen put a thicker filter in the PCV system, condensation would be almost completely eliminated and all the fuel vapors would be pulled into the air intake as intended.

[SpudRider]

Originally Posted by Lee R

I rode mine about 300 miles yesterday and filled the tube half-way. A friend also rode his with me and nothing in the tube. I diffinately ride faster and more aggressively especially on hills because I'm quite a lot heavier than he is.

Originally Posted by Weldangrind

The tube in your friend's bike might not be sealing as well at the plug. If it doesn't seal, fuel will simply drip out as quickly as it is collected.

I never collected any fluid in my down tube until after I sanded the plug, and applied dielectric grease to it, before I re-installed it. I then went for a 64-mile ride, and collected about 1-inch of clear fluid in the down tube. I was waiting to collect more fluid, before I tested to see if it were combustible. However, the dielectric grease was probably washed away, since the fluid has now disappeared from the tube, and I am no longer collecting any fluid.

It requires a very good seal to retain a mixture of water and gasoline in the down tube. My seal is good enough to prevent a submerged down tube from sucking water into the crankcase. Therefore, I am not going to modify the plug any more.

[SpudRider]

Originally Posted by detours

I found a partial solution to fuel condensation in the catch tube. Turn the PCV separator upside down!

I was thinking about my last test and realized that if cutting a hole in the filter wall increased the fuel condensation, making the filter thicker might decrease it.

I don't know how to safely add filter media in there ... but since the filter inside is shaped like a cup (open at the top), I decided to invert the separator, so it opens toward the bottom - as shown in the pic. Fuel vapor now has to travel through the side and the 'top' of the filter, approximately doubling the filter media. This raises the vacuum pressure on the other side of the filter and reduces condensation.

Long story short, it cut the amount of fuel collected in half!

The engine used to generate just over an inch of fuel in the catch tube during my 30 minute commute. After drilling the hole, I collected about 2 inches during the same ride. Now, with my replacement separator inverted, I'm collecting only 1/2 inch of fuel during the same ride.

This is very encouraging. I suppose it's possible I'm losing enough pressure that fuel vapor is staying in the crankcase, but I doubt it. I think if Zongshen put a thicker filter in the PCV system, condensation would be almost completely eliminated and all the fuel vapors would be pulled into the air intake as intended.

Thanks for posting the great information.

Perhaps the factory workers installed the 'contaminant separator' with the wrong orientation at the factory. Stranger things have happened.

I am very interested to learn the condition of your used motor oil. Please do smell the used oil, and examine the viscosity of the used oil the next time you change the motor oil.

[SpudRider]

Detours,

Does your 'contaminant separator' (CS) have a white dot painted on it? If so, was the white dot originally at the top, or the bottom of the CS?

[detours]

Originally Posted by SpudRider

Detours,

Does your 'contaminant separator' (CS) have a white dot painted on it? If so, was the white dot originally at the top, or the bottom of the CS?

The white dot on both my separators is at the level of the crankcase hose. As originally installed, the white dot faced the engine. Now it faces away from the engine. You can barely see the white dot in my image above next to the red lines that represent the filter orientation.

Basically, in the new position, you want the retaining bracket to be BELOW the crankcase hose, as in the image from the taobao site, not above it as originally installed.

My oil was fine at 2000 miles and I have another 1200 till my next change, unless I decide to go synthetic for the winter. I'll keep an eye on it.

[detours]

Actually, now I'm thinking mine was installed upside down at the factory, and my replacement was shipped with the hoses attached wrong.

Here's a pic from the CSC blog showing the bracket BELOW the crankcase line.

And here's a pic of the PCV assembly from Taobao.com, again with the bracket BELOW the crankcase line.

[Weldangrind]

Detours, has there been any change in your air filter since you flipped the separator? I'm wondering if more contamination has ended up in the filter. If it's not collecting in the tube, it must be elsewhere.

[detours]

I followed the PCV hoses and found that the crankcase vapors enter the airbox below the filter, so they are actually unfiltered except by the small filter inside the separator.

By flipping the separator, I've added a second filtration layer to the PCV flow, rather than the single layer of the original installation.

[Weldangrind]

What I mean is that if the hose is suddenly carrying more vapour, it might be revealed in the air filter. Any evidence of that?

My guess is no, since the separator is now positioned correctly.

[SpudRider]

Originally Posted by detours

Actually, now I'm thinking mine was installed upside down at the factory, and my replacement was shipped with the hoses attached wrong.

Here's a pic from the CSC blog showing the bracket BELOW the crankcase line.

And here's a pic of the PCV assembly from Taobao.com, again with the bracket BELOW the crankcase line.

I'm not surprised the 'contaminant separator' was installed upside down at the factory. As I said earlier, stranger things have happened.

From this point onward, if someone is collecting a lot of fluid in the down tube from the 'contaminant separator,' we can have them check to see if it was installed upside down at the factory.

[SpudRider]

Detours,

I just checked the orientation of my 'contaminant separator.' Indeed, the white dot is located at the top, and the retaining strap is located below the crankcase hose, as shown below.



Your 'contaminant separator' was undoubtedly installed upside down at the factory.

[Lee R]

Well I read this thread and found mine installed upside-down. Probably explains the half tube of gas I've been getting since I got it, possibly impacting the fuel economy too, i'll know after I get a few more tanks now that it's fixed.

[SpudRider]

The hose connection should be at the top, and the clamp should be at the bottom of the oil contaminant separator (OCS). I hope your photo above is the 'before' photograph, which you corrected. You shouldn't have a big loop in the hose going to the crankcase; that is a dead giveaway for the incorrect orientation.

The correct orientation for the OCS is shown in the photograph below.

[keithmaine]

my hose looks like Lee's above but the white dot is on top. Not at all like blog photo
so which is correct.

this is my bike setup