Same power, more MPG. Do it.

Check this out. I've got an XR650L with a plastic Clarke tank. I got sick of losing so much gas due to evaporation. For the sake of the smell, for the sake of Earth, and for the sake of my wallet. I decided to do a little experiment.

I routed some clear tube from the breather on the tank cap to the cab bowl overflow port on the bottom of the carburetor, allowing about 6" of hose to droop below the carb bowl. Presto, no more lost gas. I can see sometimes the fumes from the tank, or from the carb bowl re-condensing back into liquid form and resting in the section of tube beneath the carb. As soon as I fire the bike back up, the gas gets pulled right back into the system. The beauty of it is, the tank and carb bowl both allow the fuel to evaporate away into thin air anyway...why not have them vent into each other?

I ran some tests:

-I put the bike over completely on it's side as if I had crashed, let the carb drain into the line, and shook the bike around to try and flood the combustion chamber. I picked it back up, hit the starter and boom, fired right up. Ran powerful and pulled the gas right back into the fuel system. No choking, no fouling. Perfect.

-I took the bike on a 15 mile ride on/off road...full throttle at times, just idling at other times. I let it sit with the black tank in the sun. I let it sit overnight and cool to 25 degrees Fahrenheit. No problems what-so-ever.

It's amazing how much gas people are losing that they don't even know about. One 3 dollar length of tube and you're set.

I wonder if you'll have the same results trying to kick start the bike. Got a picture of the rig you've set up?

you are pertty smart, thanks for sharing!!!!!

what so share some pic and a step by step plz sounds cool

For sure, I'll get pics up tomorrow.

Smart?? I'm damn near genius.

Before I did this, I could see out of the tank cap, and out of the carb line, vapors pouring out all day like transparent smoke almost. Not good. If you've ever watched how fast fuel evaporates when just sitting there, this will make much more sense to you. If not...take it or leave it. It's a smart addition to my bike. Might work on yours too.

The carb bowl overflow port, now instead of evaporating out the bottom of the bike from inside the bowl, now being redirected back up to the fuel tank cap being sure to keep the line away from the engine and exhaust with a few zip ties...

Tank and seat back on, hook up the tube, take her for a spin and when you get back, just watch the vapors condense back into bubbles of once wasted fuel, now steadily rising from the tank (quick bubbles are hard to take pictures of)...

and collecting under the carb, waiting to get sucked back into the sytem when you fire the bike back up.

love it

I wonder if you'll have the same results trying to kick start the bike. Got a picture of the rig you've set up?

On the XR650L you've got another drain port further up in the carb. Gas will still pour out there when you lay the bike completely over. Maybe that's why it didn't flood. I tried routing to that port initially, but it screws up the vacuum. The beauty of using the carb bowl overflow, is it keeps all the evaporated fuel together between the tank and the bowl, making it more likely to condense back into liquid fuel rather than finding its way out into the atmosphere.

For sure, I'll get pics up tomorrow.

Smart?? I'm damn near genius. ?

Brilliant. ?

Cool, but with high temperatures will you end up with high pressure buildup bubbling air the float bowl and causing trouble??

Cool, but with high temperatures will you end up with high pressure buildup bubbling air the float bowl and causing trouble??

I've had no troubles what-so-ever in all kinds of conditions. The specifics if it are well discussed in here: https://www.thumpertalk.com/forum/showthread.php?t=628704

A) you have left no room for expansion of hot fuel vapors. Maybe it doesn't matter much?

? I'd rather have a one way valve on the gas cap.

A) you have left no room for expansion of hot fuel vapors. Maybe it doesn't matter much?

? I'd rather have a one way valve on the gas cap.

A) Yes you do...otherwise it wouldn't work so well

? One way valves only breath one way...tanks must breath both

C) These exact points, and many more of your doubts are thoroughly resolvede here https://www.thumpertalk.com/forum/showthread.php?t=628704