Fuel puking out overflow line

[detours]

Originally Posted by SpudRider

I'm just asking, have you tried to ignite it?

I am having a difficult time understanding how that much fuel can get past the piston rings, enter the crankcase, and exit the engine as fumes through the crankcase vent tube. In addition, as all this is happening, the engine is running great, and the bike is getting excellent fuel mileage.

Here's a pic of the liquid burning. I have no doubt it's gasoline, whatever other contaminants may exist in it. The liquid is clear amber, not milky, with no sediment or particulates.

I still have not found time to open the airbox and look for obstructions there or in the line. Hopefully I'll be able to this afternoon.

[Adjuster]

Sorry for the trouble your having but thats a cool picture.


/

[Inroads]

You won't find an obstruction because it is operating as designed.

[SpudRider]

Originally Posted by detours

Here's a pic of the liquid burning. I have no doubt it's gasoline, whatever other contaminants may exist in it. The liquid is clear amber, not milky, with no sediment or particulates.

I still have not found time to open the airbox and look for obstructions there or in the line. Hopefully I'll be able to this afternoon.

Thanks for checking, and taking the time to post the cool photo.

[SpudRider]

Originally Posted by Inroads

You won't find an obstruction because it is operating as designed.

The fuel is leaving the engine as fumes. There isn't enough pressure to force a liquid up the elevated crankcase vent. The oil separator is supposed to separate the lighter gasoline fumes from oil and other contaminants, and the gas fumes are supposed to be drawn into the air box. That is the design.



Since fuel is collecting in the bottom tube, there must be either an obstruction in the partial vacuum line to the air box, or the oil separator is defective.

[SpudRider]

Originally Posted by detours

Here's a pic of the liquid burning. I have no doubt it's gasoline, whatever other contaminants may exist in it. The liquid is clear amber, not milky, with no sediment or particulates.

I still have not found time to open the airbox and look for obstructions there or in the line. Hopefully I'll be able to this afternoon.

I suggest you also examine the oil separator. In fact, I suggest you contact CSC and ask for a replacement oil separator.

Do you notice the fuel collecting only after longer stints at high engine rpms?

[detours]

I definitely see more fuel collecting after long, high RPM runs. When I finished our 4 hour ride to Estes Park yesterday, the tube was full to the top. I think some fuel collects all the time and slowly drops out.

[Inroads]

As I see it The separator does its job as described and allows vapors by into the air box until high RPM's.In that scenario Maybe that is why the stand pipe is there to collect the solids that accumulate at High RPM's.Without the liquid standpipe than the air box could become over saturated with raw fuel instead of vapors.We may be all overthinking this one.

[Weldangrind]

You could look at it as spare bonus fuel. Handy when you run low.

[Jay In Milpitas]

I use my RX3 mostly for commuting and my freeway portion is at or near redline, but I haven't had the fuel issue that you have, Detours. Interesting problem.

Just now, while writing this reply, I thought back to when I first received mine and remembered noticing that the U shaped clamp (just above the clutch release lever) on the left side of the cylinder appeared to be bent too tight. Looked as if it was skwooshing (technical term) the hose quite a bit, so I dis-skwooshed it a little until I felt it wasn't pinching the hose but would still hold it snug.

Have you given that a look? I'd go take a picture but I just got out of the shower, it's 91F, and don't really feel like putting clothes on. Neighbors have kids, you know.

Still, if your oil is smelling of fuel, I think you have some other problem than just a breather/separator. Injector dribbling when the engine is off? Interesting.

[Inroads]

My bike experiences the same effects as detours bike does.
Standpipe is there for a reason.
When it's full you might have 2oz.of fuel...so what.
If the bike runs fine and maintains good gas mileage(60-65 mpg)
Then you need not worry.

[SpudRider]

Originally Posted by Inroads

As I see it The separator does its job as described and allows vapors by into the air box until high RPM's.In that scenario Maybe that is why the stand pipe is there to collect the solids that accumulate at High RPM's.Without the liquid standpipe than the air box could become over saturated with raw fuel instead of vapors.We may be all overthinking this one.

Of course, you are entitled to your opinion, but I must disagree. The oil separator is not designed to capture combustible fuel. It is designed to capture contaminants from the oil, and to pass gas fumes to the air box. It is not good to leak combustible fuel into the environment, nor it is not safe to collect combustible fuel in a tube near the engine.

[SpudRider]

Originally Posted by Inroads

My bike experiences the same effects as detours bike does.
Standpipe is there for a reason.
When it's full you might have 2oz.of fuel...so what.
If the bike runs fine and maintains good gas mileage(60-65 mpg)
Then you need not worry.

As far as I know, no one else is having this problem. If the oil separator is working properly for everyone else, except you and Detours, then I must assume you are having problems with the oil separator.

I strongly encourage you to examine the oil separator, and the hose leading to the air box. However, if you wish to collect fuel in the drain tube, it's not the worst thing in the world. Nevertheless, the oil separator was definitely not designed to operate in this manner.

[SpudRider]

Originally Posted by Weldangrind

You could look at it as spare bonus fuel. Handy when you run low.

That is another way to look at it.

[Inroads]

I believe that it is designed to capture some combustible fuel.You say it is a problem and I say it is not.I believe it does pass gas fumes to the air box for 99% of it but at high speed some fuel falls out of suspension and that is one of the jobs of the stand pipe...to collect it.That is my theory FWIW.
But I have enlisted the help of a guy who could probably clear this up,
Joe Berk of CSC.He rode 5,000 miles at 8,000 RPM's(also the name of his book he just wrote)With Zongshen engineers riding along with him and I'm thinking he may have some insightful info into this.
I have not seen him on this forum but he does frequent the ADV rider thumper section under our bike.
I went on there and posed the question to him so maybe we will get an answer beyond the speculation.