Gas Tank Baffling???

I personally don't use them.I'm a friction/GEBE user, as such my gas is always in a antifreeze container either between my legs at shin level (diamond frame), or behind and beneath me on my recumbent.I honestly can't tell any difference other than liquid weight.I'm a straight line flyer, so maybe hard/frequent slalom would tell different, but as a commuter, no diff.



Oh, okay, so your fuel is at a very low point. Because my tank will only be 4-5" wide, there wouldn't be much side movement, but the tank is at a pretty high C.G. and about 17" long, so it seems like it might be more of a factor and maybe a good idea to keep the fore and aft movement down.

I wrote the seller of the foam who is a landscaper by day and a 20 year bike racer by night. He said he fills the tank with the foam and has used the same foam for 5-7 years in tanks.... but he did say that he always mixes his gas and oil in a seperate jug. (not in the tank) This would be very inconvienient for me, so I think filling the tank, say....... 2/3ds with foam, might be a good comprimise helping to keep the fore and aft slosh down and still allow enough "slosh" to mix the fuel right in the tank. The cool thing is, you can always add or take away foam as desired.
 
I'm getting ready to build a composite gas tank.... approximately 4" wide X 5" tall X 17" long.
How important it would be to put a baffle or two in, to separate the tank, into halves or thirds.
Jim

I suggest yes, put a couple of baffles in, I just built a 17" long tank and at half full you can get a pretty good wave going in there.

I was going to attach a couple of sheet metal paddles to the cross struts inside, and didn't.

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Just a couple of vertical separators that don't touch the bottom of the tank will keep the waves at bay, and you don't have a tank full of foam ;-}
 
Prestone Power..........

I personally don't use them.I'm a friction/GEBE user, as such my gas is always in a antifreeze container either between my legs at shin level (diamond frame), or behind and beneath me on my recumbent.I honestly can't tell any difference other than liquid weight.I'm a straight line flyer, so maybe hard/frequent slalom would tell different, but as a commuter, no diff.

Oh yes, with that description, I remember your bike, very well.... Classic!!! Talk about an inexpensive solution for a gas tank! Good job! And, with that tank alone, you've got to put smiles on 1,000s of people's faces, as they are commuting to work. :D That's really a big reason that I'm building my bike... a cool social dynamic.
 
Baffle or Foam?

I suggest yes, put a couple of baffles in, I just built a 17" long tank and at half full you can get a pretty good wave going in there.

I was going to attach a couple of sheet metal paddles to the cross struts inside, and didn't.

Just a couple of vertical separators that don't touch the bottom of the tank will keep the waves at bay, and you don't have a tank full of foam ;-}

Yes, though I like the concept of the foam, it does feel a bit strange.... 95% of the time, I can have the fuel already mixed in my garage, but that other 5% at the gas pump does concern me, just a little. ie. will the gas and oil really get mixed up well with the foam in the tank?? So, it sounds like you're not crazy about the foam idea.... :confused:

I would definitely go for the foam, if my tank were finished without baffles, but of course, it's not, so I'll tell you about my original idea before I heard about the foam, that would be relatively simple. And, I'd like your opinion. (though, I think I already know what it is)

If you can imagine my long, rectangular tank made out of fiberglass.... (before adding the Caswell sealer) I will be cutting a rectangular access hole in the top of the tank regardless of what I do (so I can get some internal nuts on a few things; petcock etc) That cut out piece will be almost the full width and about 6" long. After it's cut out, I can hang two baffles from that cut out piece. They would not touch the sides or bottom of the tank. Before glassing it back in the tank, I'll brush a small amount of Caswell on the hanging baffles and after glassing it back in place, the Caswell will seal that replaced piece on the inside.

Okay, so what's the Verdict from you forum guys????? Foam or baffle????

1) On one hand, you've got a more traditional baffle system where the gas is free to still slosh around a bit, but mixing the fuel at the pump would be "normal."

2) Or, the foam solution, where the slosh would be eliminated almost 80% but mixing the fuel at the gas pump might be somewhat questionable.

Do you think the oil would mix in the tank with the tank half full of foam?
 
After chewing the pros and cons...... today....... (a lot of chewing) the decision is clear...... The foam in the tank makes mixing in the tank unrealistic. I'm not willing to deal with a separate mixing container, so, I will be epoxying in two (tried and true) "hanging baffles" and that will have to do.
 
I will be epoxying in two (tried and true) "hanging baffles" and that will have to do.

That should do the trick, and don't bother trying to caswel anything beforehand, you can coat everything inside once it's completed by just rolling the tank around with the caswell in it.

I question that foam for a 2-stroke mix anyway.
I can see gas alone pass in and out of the pores easily, but I wonder about cold oil in the mix.
It would be an interesting test to do in a jar.
 
Right concept, wrong foam

In order to use the foam concept for us 2-strokers, I visualize, not a closed foam like the grey foam sold above, but more of an extremely open-weave, scouring pad. Like 1/4"-3/8" space in the weave..... so the gas and oil can interact at the gas pump. More like this nylon scouring pad. Of course, the plastic would have to be 100% resistant to ethanol....(good luck) I'll let you try it in your tank first :geek:

Jim

scouring pads.png
 
Aluminum Baffle Box

just looking at threads this morning while waking up with my French roast coffee and saw my old posted question and thought some of you might be interested in seeing the final solution to my original question. I am building my own epoxy/Caswell-lined tank, and ended up buying $10 worth of aluminum sheet 6" X 18" and building a box which will be pop rivited to the cut out "door" in my tank, then replaced and glassed back in.

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The box is sitting on top of the tank (the top 4X6 door has not yet been cut out), but as you can see, the baffle box will be positioned approximately in the center of the tank, mostly to keep gas from sloshing forward and aft. I'm hoping, it will also eliminate the tendency for gas to want to spurt out of my 1/16" self-drilled gas cap breather hole. The 1/2" lightening holes were drilled to assist the gas and oil mixing in the tank, at the pump. When the foam is melted out of the tank, the top door will be cut out and this baffle box will be pop-rivited to the underside of the door and the door will be epoxied/glassed back in place, ready for the Caswell sealer.

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The rest of my build can be seen on my build thread: http://www.motoredbikes.com/showthr...olumbia-replica-with-66cc-Flying-Horse-engine Thanks for looking..... Jim
 
I have been riding years with the peanut tank. Never noticed fuel sloshing. Didn't affect the ride all. The amount that leaks out of the cap at full tank is minimal. Not to cause a drip off the side of the tank. You could always add a second washer to help with nit getting gas residue on top of the tank.
 
I have been riding years with the peanut tank. Never noticed fuel sloshing. Didn't affect the ride all. The amount that leaks out of the cap at full tank is minimal. Not to cause a drip off the side of the tank. You could always add a second washer to help with nit getting gas residue on top of the tank.

Good idea! I'll just throw my tank and baffle that I've worked on for a week, in the garbage and go back to your peanut tank. I really don't know why anyone would try to improve on the China kit.

Thanks so much for your help!
 
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