Your fuel is disappearing. Capture it.


41 replies to this topic
  • jetfuel

Posted April 09, 2008 - 10:31 AM

#21

Yes the "screw" in the side of the stock carb bowl is a drain.
You would definately not want that screw open in the configuration he describes.

  • Kenzo

Posted April 09, 2008 - 12:34 PM

#22

...and i've always wondered about the methane i've wasted over my lifetime...not to mention global warming...

i'm gunna send al gore :confused: an email with my proposal for a simular system...:thumbsup:

:thumbsup:

  • cornelieaz

Posted April 09, 2008 - 01:19 PM

#23

Do you have the drain screw open, or closed?
Dave


I didn't mess with the screw. Never have. Bike ran perfect before, runs perfect still after many miles of testing.

This is what had me confused this whole time - what you are calling a carburetor bowl drain is not a drain at all. You are connecting the fuel tank cap vent line to the carburetor overflow. Let me know if I'm way off but this is what I've gathered from both threads, at least now it makes sense to me. A friend and I got kinda excited about this idea and we will see how it works on our bikes (he's got a DR-Z 250). For $3 worth of fuel line, it would be cool to save fuel vapors from escaping and keep them in my bike. Save me money (over the very long run), save some air quality! :thumbsup:


Hell yeah. Let me know how it goes. Carb overflow, exactly. Make sure it's the bowl overflow though. I did experiment with an overflow port higher up in the mixture chamber, but that makes it run really crappy.

You still have fuel evaporating out through the main and pilot jets back through the airbox.

I would think the fuel your going to recover is very minute, probably less than the amount I see people splashing down the sides of thier cars at fill up.

But hey, if it makes you feel better thats cool..:thumbsup:


It does vent through the jets...just like every carburetor ever made with a bowl does...no big deal. Less than the splashing for sure, but far from insignificant. I would know. I see it everytime I ride. The "well everybody else does it" isn't really a strong argument.

Tell Gore I said whaddup....and he still owes me 10 bucks.

  • cornelieaz

Posted April 09, 2008 - 03:31 PM

#24

I may be wrong about what the port is called that I used on the carb. In short, I plugged the tank into the carb thingy, now I can SEE my gas gets re-used instead of lost. Works great. Bike runs perfect. Here are some pictures. Whatever it is that I have done, it works, has been tested thoroughly, and still works well. Take it or leave it. I'm going riding.

  • Ch47_pilot

Posted April 09, 2008 - 03:39 PM

#25

You're a genius. I'm gonna call you Ronco from now on.

  • DGXR

Posted April 09, 2008 - 03:52 PM

#26

People, this is a creative idea that someone came up with and wanted to share with others. Take it or leave it. Yes, it really is that simple.

  • Blacksamwell

Posted April 09, 2008 - 09:42 PM

#27

Nothing at all wrong with giving something a shot and sharing the results.

I can't tell for certain from the pictures or descriptions, but I suspect the hose is connected to the closed float drain nipple. The long blind hose winding down through the shade and relative cool underneath the plastics would tend to capture the vapors by allowing them to cool and return to liquid form. But it might just do the same thing if you simply plug the hose and route it similarly and keep it away from hot things like the headers.

A simple test to see if this is the case on the PO's bike would be to pull the end off the gas tank and carefully pull a little vacuum with your mouth. If the condensed fuel moves up the hose freely then it's legitimately connected into the bowl interrior. I'd be curious to see if you pull air or more fuel. If it doesn't move then it's likely connected to the closed float bowl drain.

Either way, the hose should capture at least some vapors that would have wafted away otherwise.

Enloy your mod. :thumbsup:

  • Kenzo

Posted April 10, 2008 - 06:19 AM

#28

Tell Gore I said whaddup....and he still owes me 10 bucks.



HAHAHAHAhahahaaaa...just a little levity


it's a feasible concept to stop emissions (just like a cars gas cap with a one way valve) but u cud end up with venting problems since you've just added a long length of hose plugged at the end(closed bowl drain fitting).

a check valve on the gas cap with a tee below it routed to the airbox wud probably be more sound technically...but IMO ur chasing a few pennies a day max...

keep us updated...


:thumbsup:

  • tobinbakner

Posted April 10, 2008 - 06:42 AM

#29

The tube is connected to carb bowl overflow. The drain and the overflow are the same hole. Inside the carb bowl is a brass tube that runs up to above where the fuel is supposed to sit. The drain is closed unless you open the screw but passage is always open through the over flow. The only problem I see is if the float should get stuck the fuel has nowhere to go except into the engine. depending on when and how fast the flow is the consequences could change. Here is a small attempt with paint to show what I mean.


Posted Image



Tobin

  • Kenzo

Posted April 10, 2008 - 07:13 AM

#30

The tube is connected to carb bowl overflow. The drain and the overflow are the same hole. Inside the carb bowl is a brass tube that runs up to above where the fuel is supposed to sit. The drain is closed unless you open the screw but passage is always open through the over flow. The only problem I see is if the float should get stuck the fuel has nowhere to go except into the engine. depending on when and how fast the flow is the consequences could change. Here is a small attempt with paint to show what I mean.

Posted Image

Tobin


yup...ur correct...:thumbsup: ...that is always open and one cud assume it's connected above with the carb vent...hummmm...the plot thickens

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • cornelieaz

Posted April 10, 2008 - 12:06 PM

#31

The tube is connected to carb bowl overflow. The drain and the overflow are the same hole. Inside the carb bowl is a brass tube that runs up to above where the fuel is supposed to sit. The drain is closed unless you open the screw but passage is always open through the over flow. The only problem I see is if the float should get stuck the fuel has nowhere to go except into the engine. depending on when and how fast the flow is the consequences could change. Here is a small attempt with paint to show what I mean.


Posted Image



Tobin


YES! Thank You! Man, illustrations...that's what I should have started with all along. Well said.

  • Blacksamwell

Posted April 10, 2008 - 12:57 PM

#32

The tube is connected to carb bowl overflow. The drain and the overflow are the same hole. Inside the carb bowl is a brass tube that runs up to above where the fuel is supposed to sit. The drain is closed unless you open the screw but passage is always open through the over flow. The only problem I see is if the float should get stuck the fuel has nowhere to go except into the engine. depending on when and how fast the flow is the consequences could change. Here is a small attempt with paint to show what I mean.


Posted Image



Tobin



Thanks, that helps a great deal.

So the long hose from the fuel cap is connected to the overflow tube which runs up through the fuel to the atmosphere above the float boal which is vented to atmosphere, right? So other than the pool of liquid fuel settling in the long hose it's still just a path to atmosphere? Assumably the fuel vapors are evaporating off the back side of the liquid fuel in the line and escaping up the overflow tube and out the float bowl vent lines, right?

Also... If the overflow tube is above the level of the fuel in the float bowl then how would the carb suck in or utilize any of the fuel in the line below the carb? Only when enough fuel has filled the line so that gravity can push it up and over the overflow tube will the gas in the line make it into the carb. And if that's happening the floats should have the float valve closed and that extra fuel goes where? In extreme cases wouldn't it push up through the jets and run down your intake to sit on the top of the piston or behind the intake valve since you've blocked the normal overflow route? What happens when you take a spill and the bike sits upside down for a moment or two? Are you risking a raw fuel hydro lock in that kind of situation?

  • Kenzo

Posted April 10, 2008 - 01:00 PM

#33

...so do u have the carb vent line(s)connected w/ a tee and one end is under the seat the other end is down below the swingarm piviot???

...this is the stock setup with the exception that the carb drain/overflow line is also tied in...

...so it sounds like the tank is now vented through the carb vent...in a round about way...that is IF the bowl is vented with other than the drain/overflow connection which is no longer vented in a true sence...hummmmm...


:thumbsup:

  • Kenzo

Posted April 10, 2008 - 01:16 PM

#34

Thanks, that helps a great deal.

So the long hose from the fuel cap is connected to the overflow tube which runs up through the fuel to the atmosphere above the float boal which is vented to atmosphere, right? So other than the pool of liquid fuel settling in the long hose it's still just a path to atmosphere? Assumably the fuel vapors are evaporating off the back side of the liquid fuel in the line and escaping up the overflow tube and out the float bowl vent lines, right?


...only if the bowl is also connected to the carb vent...the drain/overflow wud have provided venting before it was routed to the tank vent...


Also... If the overflow tube is above the level of the fuel in the float bowl then how would the carb suck in or utilize any of the fuel in the line below the carb? Only when enough fuel has filled the line so that gravity can push it up and over the overflow tube will the gas in the line make it into the carb. And if that's happening the floats should have the float valve closed and that extra fuel goes where? In extreme cases wouldn't it push up through the jets and run down your intake to sit on the top of the piston or behind the intake valve since you've blocked the normal overflow route? What happens when you take a spill and the bike sits upside down for a moment or two? Are you risking a raw fuel hydro lock in that kind of situation?


...the bottom of the jets sit in the fuel and the venturi effect draws the fuel through the jets...

...but i agree in some cases there may be carb venting issues...

...the fuel observed "recondencing" may be in part fuel sloshing into the overflow tube that is being captured rather than drained...hummmmmmm...

:thumbsup:

  • cornelieaz

Posted April 10, 2008 - 02:13 PM

#35

Ok, Bare in mind, if some of this seems impossible, or confusing, or entirely false, just get a hose, hook it up (it takes 2 minutes) and watch before your eyes as the mystery unfolds.

-Yes, the tank vent is now connected to the atmosphere above the fuel inside the carb bowl. The drain screw is all the way in (closed). I backed it out and fuel does pour into the tube which would make the bike run very poorly, if at all. I didn't try.

-No, it is not a completely sealed system. The idea is to merely encourage the vapors to re-condense, which they will do successfully in the connecting tube. Fuel systems MUST breath. In the event that there is too much pressure it will vent...God knows where, but it does. Carb bowls always do, that's a good thing, if you prevented that, your bike would run like crap. Maybe it bubbles like a bong pushing air up through the submerged jets...maybe there are other openings. I don't know. I DO know however:
A. before I hooked up the tank to the carb, I tested that port on the carb by slowly sucking and blowing air to make sure that the air did move. It does, and happens to be VERY vapor rich when air is coming out due to the fact that it is the atmosphere directly above the fuel in the carb bowl. This port does vent out vapor rich air on it's own, and in the event that the tank does not pull them back in immediately, you will see them turn back to liquid and rest in the line.
B. My tank does not swell, nor does it contract at ANY time during operation or at standstill. I know what it looks like when it does because prior to this I used to just plug the vent on the tank after I went riding. Lets hear it for dumb ideas. :thumbsup: Not good.

-No, the fuel collecting in the tube is not due to splashing. You will see the bubbles moving through the tube up out of the tank cap as it does it's thing. Sometimes the bubbles move away from the carb depending on which way the pressure needs to go at that given moment. The vapors condense to liquid in the tube, but will return to your system as vapor. That's the magic: that when the tank breathes in, it pulls very vapor rich air right back in. When it breathes out, it is more likely to return to liquid form, not be lost and be pulled back in next time the system breathes either into the tank, or into the carb bowl. I tend to think that it is a significant amount of fuel...but I suppose that depends on your definition of "significant". In my book, being this easy to rig up, every bit helps...especially if you do alot of riding as this effect is most active after a ride.

Ok, I think that covers it. Give it a shot. It's science baby.

  • Denn10

Posted April 10, 2008 - 02:23 PM

#36

tell us a little more about this coating or whatever it was that you did to your tank to supposedly stop vapors from seeping thru? Website or something?

  • cornelieaz

Posted April 10, 2008 - 02:37 PM

#37

tell us a little more about this coating or whatever it was that you did to your tank to supposedly stop vapors from seeping thru? Website or something?


Yeah, I did lots of searching through the internet and found alot of people talking about using floor was as a plastic sealant. Supposedly it's non-gasmermeable due to it's "sealant" nature, but I don't really have the tools to test that claim. Lots of people were using it to hold on tank graphics that kept peeling from the hydro-carbon seepage of plastic tanks. There may be better products, but this is what I used:
http://www.f-15estri..._01/matt_01.htm

  • DLS524

Posted April 11, 2008 - 05:22 AM

#38

I have a 2006 XR650L with the same tank. I am planning on trying this on my bike. Does anyone that has done this taken data on the fuel savings? I will run a full tank thru before and after the mod to see what the benifits are. As far as the tank sepage. Does anyone have any close up pictures or more detail on how to coat your tank so that it will last and how they went about doing it. This is a GREAT topic with the high gas prices on how to squeeze the MPGs out of our pigs!! GREAT JOB!! I am thinking about looking at this application on my CRF450R also.

  • Blacksamwell

Posted April 11, 2008 - 06:27 AM

#39

Great thread. Thanks for working out all the details with us.

  • ghrati ghoti

Posted April 11, 2008 - 07:29 AM

#40

Great thread. Thanks for working out all the details with us.


+1 I concur!





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