Adding an evaporative fuel canister


23 replies to this topic
  • cornelieaz

Posted March 26, 2008 - 09:58 AM

#1

Yeah, so call me crazy, but I'm looking for a way to capture the fuel vapors being vented out my tank cap and re-use them in the fuel system. I don't like the smelling like a gas station all the time, and it'd be nice to not lose expensive fuel due to evaporation. Perhaps I may need some sort of charcoal canister...the same system that street bikes and have? Can the California model stuff be added to a non-California '98 XR650L? What all is included to make the system work? Ideally, I would like to have the fuel system be entirely enclosed, but I'm not sure that's possible. If not, what's the closest, or next best thing? Thanks for the input.

  • XR650L_Dave

Posted March 26, 2008 - 10:12 AM

#2

It may help with the smell, but a charcoal canister system won't usefully burn the captured fuel. The fuel gets burned, but since the bike has open-loop jetting, it'll just run a bit extra rich while the canister is being purged. The fuel is still 'lost' as far as howm-many-miles-you-get-out-of-a-tank is concerned.

If you had all the bits, you prob . could add the cali stuff, but I think the cali L carbs have an extra vacuum port?

Dave

  • cleonard

Posted March 26, 2008 - 10:18 AM

#3

On the positive side, I'm sure that you can get the parts for free!

  • RipperFox

Posted March 26, 2008 - 10:21 AM

#4

Are you talking about the vapors produced while riding or whille parked.

While riding, you could just run a longer vent line from the gas cap (from a cali model bike)to air box. Drill hole little smaller than the vent hose and stick it in.

Cant think of any problems that would cause..

And there are probably a BUNCH of people that would trade you a Cali carb for yours.

  • cornelieaz

Posted March 26, 2008 - 10:55 AM

#5

It may help with the smell, but a charcoal canister system won't usefully burn the captured fuel. The fuel gets burned, but since the bike has open-loop jetting, it'll just run a bit extra rich while the canister is being purged. The fuel is still 'lost' as far as howm-many-miles-you-get-out-of-a-tank is concerned.

If you had all the bits, you prob . could add the cali stuff, but I think the cali L carbs have an extra vacuum port?

Dave


I'm for sure not going to replace the carb to pull this off. Is there a similar alternative to the canister?...maybe some way I could route the breather to help keep the vapors in the fuel sytem? Some kind of vapor filter maybe?

On the positive side, I'm sure that you can get the parts for free!


Yeah...funny for sure. Hell, I could get a whole mountain of free parts (+ shipping no doubt).

  • cornelieaz

Posted March 26, 2008 - 11:12 AM

#6

Are you talking about the vapors produced while riding or whille parked.

While riding, you could just run a longer vent line from the gas cap (from a cali model bike)to air box. Drill hole little smaller than the vent hose and stick it in.

Cant think of any problems that would cause..

And there are probably a BUNCH of people that would trade you a Cali carb for yours.


While riding and parked. There's plenty of venting going on all the time...especially when that black Clarke 4.7 is glistening in the sun. I can see the distorted veiw through the vapors rising steadily from the cap...kinda like a mirage on a hot desert road. I would be open to swapping carbs if that's what it took. I may be posting a "wanted" ad soon.

  • Denn10

Posted March 26, 2008 - 12:13 PM

#7

i would think the only thing you would want to do is route your vent hose to your air filter like already said.

  • cornelieaz

Posted March 26, 2008 - 12:27 PM

#8

i would think the only thing you would want to do is route your vent hose to your air filter like already said.


Right, that would be effective while the bikes running, but that doesn't stop the gassy fumes from seeping out all day long when it's just sitting there. That's what I'm trying to contain. The airfilter element isn't near dense enough to pull that off as far as I know.

  • XR650L_Dave

Posted March 26, 2008 - 04:20 PM

#9

A dirt-simple method would be to run the breather hose to a charcoal canister, then you just need to pull just enough vacuum on the canister while riding to such the fumes out of the charcoal.

If your bike is sitting in the sun, its a guess as to whether a std L canister would catch it all enough to prevent any smell.

Dave

  • asf

Posted March 26, 2008 - 05:37 PM

#10

Get one of those speed bleeder hoses and invert the valve so it lets air in but wont let air out. When vacuum is created by the gas tank running gas out to the carb, the tank can still breath in. But when your fumes want to get out, the valve should not let it. Would that work?

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  • XR650L_Dave

Posted March 27, 2008 - 08:30 AM

#11

Get one of those speed bleeder hoses and invert the valve so it lets air in but wont let air out. When vacuum is created by the gas tank running gas out to the carb, the tank can still breath in. But when your fumes want to get out, the valve should not let it. Would that work?


That will work, but if its cool at night and a lot of air gets sucked in, then during the day its 100 degrees out, and its a blank tank sitting in the sun, that could be a fair bit of pressure.

With the fuel on, might even shoot some gas past the needle.

How much pressure would it take to permanently bulge a 110 degree plastic tank?

Dave

  • Frank ZX

Posted March 27, 2008 - 12:12 PM

#12

:prof: No offence,but it does sound crazy,but you could have a small ball valve to close the vent when your bike is parked,
then when the bike is running open the valve to vent vapors to the air box to be burned.
I guess all of us are a little crazy in our own way.

  • Itchykawa

Posted March 27, 2008 - 04:42 PM

#13

Trade it in for a California model. :prof:

  • cornelieaz

Posted March 27, 2008 - 05:02 PM

#14

Get one of those speed bleeder hoses and invert the valve so it lets air in but wont let air out. When vacuum is created by the gas tank running gas out to the carb, the tank can still breath in. But when your fumes want to get out, the valve should not let it. Would that work?


I had thought of that...tried something just like it even. The problem is that the tank builds up enough pressure from heat and movement to force too much gas into the carb bowl and it overflows. You come back to a nice little pool of gas under your bike.

I like all the ideas though. Dave's super simple canister idea sounds like it might work. Now to locate a canister...

  • dldavis_66

Posted March 27, 2008 - 07:02 PM

#15

Here's an idea...been thinkin about trying it out on my bike:

I'm pretty sure all the airboxes are configured the same for your '98 as they are for say the '07. There are 2 nipples on the front side of the airbox: one for Crankcase breather/Oil-Air Separator line, the other for the Smog pump (I dunno if the '98 L has a Smog pump). My plan is to run an extended Gas cap line to the open nipple on the front side of the airbox, maybe drill out that rubber plug that came with the Smog Blocking kit, get a small plastic nipple that will squeeze inside of that and then connect the Gas cap line to that.

That would help with the vapors from the tank, but I don't think that would solve the problem of gas expansion overflow. I certainly don't want overflowing gas going into the carb when the bike is running. I reckon it all depends on how full the gas tank is.

I dunno bout other folks, but I would rather fill my tank up to about 1/2 inch from the top and not to the bottom of the neck like it says in the manual. I would probably have to fabricate some type of over-flow canister and put it somewhere in between the gas cap and the airbox. The stock canister wouldn't help. I'm pretty sure it's sole fuction is to just collect vapors from the tank(for return back to the carb) and any liquid gas overflowing from the tank(over-expansion) gets drained (wasted).

Any other thoughts on this, anyone???

  • tgstoken

Posted March 27, 2008 - 07:05 PM

#16

I have the easiest and least expensive tip. Just learn to enjoy smelling like gas.:prof:

  • cornelieaz

Posted April 03, 2008 - 03:33 PM

#17

What do you suppose would happen if I routed the tank breather to the bottom of the "Y" carb overflow joint? Maybe then it would just vent out through the jets? That seems pretty enclosed...maybe I'll just give it a shot and see what happens. I'm feelin dangerous.

  • asf

Posted April 03, 2008 - 03:41 PM

#18

Since you have vacuum coming from the vent tube on the tank while the motor is running, wouldnt you be sucking fuel out of the bowl? That sounds sort of :prof:

  • cornelieaz

Posted April 03, 2008 - 03:49 PM

#19

Since you have vacuum coming from the vent tube on the tank while the motor is running, wouldnt you be sucking fuel out of the bowl? That sounds sort of :bonk:


Well, not always. Sometimes the vent is pushing out of the tank, sometimes sucking in, depending on riding/temperature conditions. The vent is always slow and mild enough though that it seems worth a shot. If the carb drips gas out the vent, then the evap would just end up back in the tank where it came from. When the tank throws out vapors/fuel out the top, it would just end up getting combusted.

I'm going through it all in my head, tracing all the carb lines, and I'm probably missing something, but I think I'm gonna go pick up a nice long tank vent tube and see what happens.

I'm entirely open to the probability that its a stupid idea, but if it works then hot damn, I'm set! Seems to make more sense than running straight tube from the crankcase to the airbox, and plenty of people are cool with that....not sayin anything, I swear :prof:

  • cornelieaz

Posted April 04, 2008 - 04:01 PM

#20

SUCCESS!!!! ...Didn't use "Y" joint, that just vents back out into thin air. I routed the tank cap breather hose directly to the nipple on the bottom of the carb bowl...the overflow port. Perfect. I can see the gas vapors accumulating back into liquid and resting in the line. No operational problems what-so-ever during a 10 mile on/off road ride. All that wasted gas that previously just evaporated away like dollar bills in the wind, now contained and being re-used in the engine. What is more, the lost gas that evaporated out of the carb bowl through the overflow port is now also contained. I even layed the bike over on the ground, tried to get the thing to flood, picked it back up, hit the button and she fired right up. It only took a couple minutes more riding to pull the drainded gas back in. Damn I'm smart. Amazing how much gas everyone is losing without even knowing about it. One $3.00 length of hose and I've got more MPG, cleaner bike, cleaner air, and all while not sacrificing an OUNCE of performance. Do it.





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