This is for the busa. Evoteck gas cap. Which installation is correct?

There are two holes in bottom of the the recess that the fuel tank cap ring fits into. One is a breather and the other is an overflow. The Evotech gas cap has a rubber tube that is supposed to be inserted into one of these holes. I presume it would be the breather hole. Can anyone tell me where the correct hole for the rubber tube is located?

---

BUMP

---

1. I follow hose to the gas cap housing:
a. There are no holes for the gas cap?
b. There is only this side hole at the housing.
c. The hose goes to the ground or to the tank is the lineup?

2. I lay the gas cap housing down and match:
a. The housing only lines up one way; the hose finds no hole; is the wrong unit for year tank?
b. I line the hose up to the tank hole; kinks the hose as I line up the screw holes with a twist.
c. It only lines up one way is the hose has no kink and drops in a hole, the screws line up, it fits the tank, etc.

3. It fits in hole 1 fine and hole 2 also:
a. The housing is a perfect triangle fit no matter which hole.
b. The tube does not kink and lands right down the rain vent.
c. The tube lines up without a kink is inside the gas vent hole.

4. I can choose a 3rd vent.
a. My tank vent is exposed to air, go wipe my bike down and see how much fine dust clings.
b. My tank housing needs a vent and a cotton filter rolled up down that housing plastic hose.
c. I find one of them there plastic L hose fittings and wrap the hose around under the housing that says:
1. My ground hose vent feeds the hose with the 100% cotton briefs holding back the dust, can still breath
2. My tank vent did have a rubber ring around that for dust and slosh, so I cap that off closed.
3. My vent runs to the cap and has a 2-vent-system is a diaphragm opens under vacuum and the other side is the equalizer diaphragm; with the spring and hole on the opposite side is now neutralizes the tank this way.
4. My filling of the tank is an abrupt brake issue, the gas flies up the cap/vent?... the gas moves thru the cotton, out the tube, down the water vent or ground vent or gas tank vent [I did not close off is] all in one, meaning, down two tank vent holes.

Make sense no kink whatsoever we go modding with an L fitting small enough to make the U and not V the hose so it stops flowing?

OR... Cut down or find a water bottle screw top. Pack the cap with a 100% cotton ball, remove the plastic hose, lay the cotton cap over the vent, meaning, forget the hose going down a hole. Just make sure the cotton is acting like a filter, not a capped off vent. Double up two caps over each other with the cotton inside and drill two holes at the sides of the caps so those are the vent holes for air.

Meguyver thinks out of the rear end and that took a fudge knuckle we go picking for orifices and venting relief stations.

---

I was about to send you a PM to coment on this Hub. Thanks for the reply. So far, I got zip on hayabusa.org.

Interesting point about possible dust contamination. Yup, there will always be some fine dirt found in the bottom of the gas cap ring recess after a couple years of use. I wiped it away for the pics. We do have a replaceable gas filter on the busa but why clog it up?

1. I follow hose to the gas cap housing:

There is a hole from the yellow rubber tube to the inside of the filler neck of the gas cap housing.

"c. The hose goes to the ground or to the tank is the lineup?"

That's what I'm wondering. Is this tube meant to let air in/out of the sealed tank or is it meant to provide an outlet for a fuel overflow?

2. I lay the gas cap housing down and match:

The hose is flexible enough to go down either hole. It's position does not seem to favor one hole much more than the other.

3. It fits in hole 1 fine and hole 2 also:

Yep, either one. One is a tighter fit but not tight enough to seal.

Before going to modding, lets try to figure out how this thing was designed to work.

If this is a fuel overflow vent, it should go down one hole and if it's just and air vent, it should go down the other.

According to Corey at Motomummy, this tube is just and air vent so you don't airlock the cap. You do not need to put it down either hole, just wrap it around the outside of the housing in a way that it will not get kinked. I say, if the tank has an air vent to the cap, it should be sealed to the cap (like the OEM one is with the grommet) so only air can get in.

For now, lets identify the holes:

There is a rubber grommet on the OEM cap and it adjoins one of the holes sealing the hole to the gas cap. That must be the air vent hole, right?

The other hole is in the bottom of a small trough (you see that in the pic). That must be a rain water drain hole, right?

* Last updated by: Rook on 6/5/2015 @ 4:38 PM *

---

There is a rubber grommet on the OEM cap and it adjoins one of the holes sealing the hole to the gas cap. That must be the air vent hole, right?

Right. That's where the vent is for the OE gas cap housing. So if hindsight won't show you how to decipher two holes, I take my OE gas cap housing, lay my housing down on the mount holes, see my rubber seal cover either side of the tank vent holes... my guess is drain to the ground for rain/washing bike is left side, I set my kickstand down, bike leans over, I would have all my ground drains to the left side... think.

So my guess is the same as the 14, with the weather/wash drain hole is left side. How side am I?

The other hole is in the bottom of a small trough (you see that in the pic). That must be a rain water drain hole, right?

When I go back to the rear of the tank and see those tubes come out of the back, I connect a plastic hose in the end, open the gas cap, blow into the hose. And whoever blows out the kleenex I have stuffed in there lightly, I give a hearty exhale, the odds of that paper flying out that hole shows me who is whom?

According to Corey ...the para is... "this tube heads up the cap to atmosphere for relief.' 'This is so you don't airlock the cap housing."

IF SAY:
I would now follow Corey and seems this modding does not need to buy anything.

The Corey Curl is just that... a curl. So I'd now snip a chunk of hose, find a gold tee, run the short snipped hose up the tee; send it down the tank vent hole. The push of the plastic up the taper of the tee will cause it to set in that memory.

The tee falls out, that says the taper won't fall down into the pipe as it does now. If I want to be anal-trick, I keep snipping the tee down until I can lay the housing over it; the slight push down on the head of the tee; sends the [dust] sealing effect locked in place.

So far, I got zip on hayabusa.org.

Lets look at the holes. One is sort of large... means fast escaping rain to dump in. The cleaner made taper for the smaller atmo hole, it would take even a pin hole to keep the lock from happening. So the second guess is big hole=water/small hole=air. How close am I now times two ways of looking at it... meguybeer?

---

The other hole is in the bottom of a small trough (you see that in the pic). That must be a rain water drain hole, right?

Or your 3rd way of looking at it... I missed that one, concentrated on the taper and size of the holes instead. But look at the trough on the left side is there you go.

---

"correct hole for the rubber tube is located?".."One is a breather and the other is an overflow"...I think it's just the ONE line and hole Rook.That other smaller hole may be to help equalize the pressure(if there was any)between the tank(painted outside part) and the liner.

It's the hole at the REAR of the cap there(see diagram).

That's the one you want to run that yellow hose into(apparently it'll fit the ID of that factory hose[like you have it now])?Looks like your tank has but ONE vent line doubling for an overflow(into the canister).You can see that 'pipe' isn't too long,maybe an inch or so...just cut the yellow hose so it's lengthwise matching(or close to it)the length of that metal piping there.That's all it needs to be...any overflow will drop right in there.as well as the venting action of the canister line...see where it's pulling fresh air in?(at the canister).

When I looked at the parts diagram on the fiche,that 'fuel/vapor' separator had two lines meeting up in that space between the outer shell and the liner.Right where that 'valve' is.

I would correct what I said before...I'd put it in that upper hole.Is there just the ONE nipple on that cap you have there?And the lettering goes to the lower part of the cap?Where is the nipple at?Top?or bottom.Looks like either hole will go the same place...into the separator valve.

* Last updated by: Grn14 on 6/5/2015 @ 10:14 PM *

So my guess is the same as the 14, with the weather/wash drain hole is left side. How side am I?

I think you got it. I never considered that point. Why would you pick the RH side for a drain hole when the bike leans to the left while on the side stand?

the slight push down on the head of the tee; sends the [dust] sealing effect locked in place.

Yes, I would not think overly fastidious if that tube was loose fitting in the hole. It seems to have swelled up a little now from exposure to gas and fumes. It fits snug in the RH hole which is the one I think we are now going for.

How close am I now times two ways of looking at it... meguybeer?

The larger hole would be more necessary to drain liquid. The air hole does not need to be large. Right!

concentrated on the taper and size of the holes instead. But look at the trough on the left side is there you go.

Hole size + trough = water drain.

Can't you see if one or the other holes in that gas tank have a hose attached under there?Just under that lip

HA! Good idea, Grn, I never looked. However, the hoses would probably be concealed between an inner and outer shell like you mentioned. I would expect to find both holes to have a hose if they are visible. The tank has two nipples at the bottom left front, each with a hose attached. The 14 also has 2 nipples (3 on CA models) but they are located at the back. One is breather, one is water drain. As Hub mentioned, he would place a small piece of Kleenex in the holes and go down and blow into one of the two hoses to see which ejected the tissue. There are 2 hoses at the back sticking through the belly pan. I know one serves as an overflow cuz I have seen fuel come out of it when I overfill and the bike warms up.

"correct hole for the rubber tube is located?"..doesn't the Busa have a diagram of the tank?Surely it will show a nipple?

Yes, however the diagram is a straight on side view showing two hoses. They are labeled but because they are positioned directly opposite of one another, they overlap as viewed from the side. It is not clear which hose goes to which hole. We would need a labeled drawing of a back or top view to show that....or maybe if they made the illustration larger, they could have indicated more clearly which hose goes to which hole.

Anyway, I think we have pretty much determined that the RH hole is the vent hole. It is the smaller of the two holes. It does not have a trough and it is not on the left side of the bike. It has the rubber grommet on the OEM cap. The grommet connects and seals a pathway from the hole to the gas cap. The OEM cap has a tiny hole in the bottom looking down into the tank. Vacuum from the tank draws air through the small hole in the cap. This hole leads to the grommet which adjoins the vent hole in the tank. There is a hose attached to the vent hole to admit air from the outside.

We know what hole does what. Now what is the yellow tube on the Evotech supposed to do? It is a vent hole for air. It is configured just like the OEM cap except instead of a grommet, we have a yellow rubber tube. The only question I have left is, "does the fuel tank vent also serve as the fuel overflow?" If so, I think we have found the right hole, fellas. The yellow tube that comes out just below the gas cap would also be the best place to expel an overflow. It's at the highest point in the fuel tank.

So, is the air vent and the overflow exit one in the same or is there a separate tube for overflows?

---

"I would expect to find both holes to have a hose if they are visible"...they're NOT visible...the Y connects lower in the liner. Then heads for the canister.That's what the parts diagram is showing.I went to CheapcycleParts,2008 Suzuki Hayabusa,Fuel tank.That pic came off the web...so that's a side view.The fiche shows a three dimensional pic.I couldn't copy the picture,not all of it,IDK why.Go there...you'll see what I'm talking about.The liner under there,where you can't see,has TWO nipples coming off from the valve(see diagram)...and meeting a bit down the line.Two hoses connecting.So I don't think it matters which one you install that hose in...The 'separator valve'....that's it just under the cap there.You can't see it cause the outer tank shell is mated up to the liner right there.(at the filler tube)(the holes piping attach to that valve).Apparently they BOTH have a hose ,and connecting at the valve.Those holes there have metal lines welded in....Can you see into the hole and see if they have a welded small pipe?It goes straight down just a bit then curves away and down.Least it looked like it did?Maybe a longish ziptie,slide it in there and see if it follows a pipe.It'll probably stop within an inch or so,at the valve.The valve is right there according to that diagram on the Cycleparts site.Also shows the lines coming from the valve and fittings.Connecting into the canister line.

The 'breather' line is the same 'Surge' line.You can't see the rest of the canister,but it's showing fresh air entering at the front of it.(those two arrows coming in)

* Last updated by: Grn14 on 6/6/2015 @ 12:09 AM *

So, is the air vent and the overflow exit one in the same or is there a separate tube for overflows?

3 Holes Think:

1. The rain vent is a given.
2. The filler hole is a given.
3. The metal hose in the tank is for looping closed the vent and should be closed, we are now a gas lawnmower tank is the cap is exposed to the water troth is the vent. The 3 screws cannot close off the air, but that oring around the housing is going to close down on the filler hole and seal that area only. The metal gas hose is like drilling a hole in the top of the tank for a vent? What for?

The new gas cap has two holes under it, go look. Suck on one side, blow on the other or reverse your lungs or spin the cap 180 and line your blow out the cap is if the cap has an oring and seals itself to the housing filler hole, you know the vent is now two you do not need the gas overflow vent to be open.

Think old style gas cap from a car, old bikes, old lawnmowers is one hole for the tank. You are going to wake up tomorrow and ... Know how simple this was and dot org could not come up with a simple lawnmower cap my bike off theory.

So, hose swelling, golf tee planting a simple squeeze you do not collapse the hole and now the OE has a gap when the rubber lays down on it... or off it more likely. We there yet? Sleep on it. Walk away and tomorrow...

---

Yup...there must be a gap.It's not totally snug on that filler neck.Guess on this bike,when they say.."fill only to the bottom of the filler neck"...they aint whistlin Dixie;)Either that or take no curves with a FULL tankLOL

* Last updated by: Grn14 on 6/6/2015 @ 12:25 AM *

IPA >>> 'Vac Damper'... NO SHIT. Did you catch the fat vac take up some damp in the low fluid vid? Smoothed it out like wow... So it wasn't me not catching that change in the assfactor... well I'll be... A simulator... not even close but a change none the less. The small gauge is too small a toilet, but add the big swinger is pool size and that vac taking up that pull... I'd have to close PAIR and take a read on both the flash and OE. I did swap out the return ride, not sure but it kind of hides it, but where in the AFR is all this so my assfactor lies to me or not?

---

"or maybe if they made the illustration larger, they could have indicated more clearly which hose goes to which hole"...I think they showed it like that to indicate...it doesn't MATTER which hose goes where at the cap..They BOTH have a hole for venting,whether liquid,or vapors.I'd guess the larger one would be for the liquid.Since it's gonna slosh around in there if you fill the tank all the way up.

* Last updated by: Grn14 on 6/6/2015 @ 9:11 AM *

Thanks for all the input, guys. I'm going to have to take a while to digest this because I'm busy with the kids this weekend. Currently, my thinking is to use the vent hole shown in Grn's diagram. There must be a hose coming from each hole but it is not shown in Grn's diagram. The diagram in the SM shows 2 hoses, one called fuel tank breather hose and the other called fuel tank drain hose. They are overlapping however so I can't tell which goes to what hole. The drain hose must be only for the water drain, not fuel overflows. With a gasket sealing the filler neck to the tank, no gas could get to this hole from the OEM cap if there was an overflow. You remember the OEM cap has the grommet conecting the filler neck to the vent hole. That would also drain fuel overflows with the OEM cap. The OEM cap could not have drained overflows into the drain hose because there is no grommet or anything connecting the inside of the tank/filler neck to the drain hole. That's just for water that seeps between the exterior of the tank and the fuel cap ring.

Now that the OEM cap is replaced with the Evotech and we have a rubber tube that could reach to either hole. I don't see why you couldn't use either hole to drain fuel overflows but it is better to use the breather hole as the overflow exit like the OEM setup does. The drain hose may present a chance (remote as it may be) of sucking trapped water in the drain hose back to the tank because by inserting that rubber tube, you have now turned it into the vent/fuel overflow + it's too big to prevent water from draining past the yellow tube. You now allow the vent hole to drain rain water as well and it does not seem to be designed to drain water as effectively as the intended drain hole. Also, the yellow tube fits snugly in the vent hole now that it has swollen a smidgen. It should seal out any dust. Another thought: Where does the water drain hose exit the bike? If it's near the engine, you would not want to use it as a fuel overflow. Aftermarket gas cap but it is best to make it work the same way the OEM cap works.

I will sketch up my own diagram to illustrate how this all works. This should actually come in handy for ZX-14 aftermarket caps because some of them probably have a rubber hose on them that should be routed to the proper hole. My LighTech cap does not have a hose for overflows. It just has a small vent hole to let air in/out and I guess if there is an overflow, it drains down into the ring recess and goes down both holes.

* Last updated by: Rook on 6/6/2015 @ 6:25 PM *

---

Hell...I'm way too confused at this point.It shows the two lines(Fuel/Vapor..and 'breather') intersecting into the one downstream.Which is heading into the canister.Fuckin Busa.;)

Hub says..."3 Holes Think"...it doesn't have three.Only two into one..from what I see in the parts diagram online.

* Last updated by: Grn14 on 6/6/2015 @ 7:23 PM *

Look at my pictures of the part. There are two holes there. The others are screw holes. Your diagram shows only one of the holes. The fuel/vapor/breather.. That's what I'm saying, the breather pipe and the overflow pipe are the same pipe. The other one not shown in your diagram is the water drain. The small hole in my pic is the fuel / vapor/ breather. The large hole is the water drain. I think it would work fine if the the yellow tube was inserted in the water drain. Then it would drain water but it would also drain fuel if there was an overflow. The water drain should work fine to let air in for a vent also. But I don't see any reasin to do that when ther is a special hole already there for the vent/ overflow. Also the canister thingy. That must be ther to condense vapors and use that gas instead of venting it to the outside. Might as well follow the function ofthe original desin=gn even if I have anaftermarket gas cap.

---

Hook the aftermarket up so it does the same thing the OEM cap and there's no need to ponder how/why it works.

---

I think so...You can see though in that picture of the two pipes under the cap(in the liner).Look at the one on the left side there...it's going forward farther than the right one.That's the top hole...the small one.The diagram isn't showing that because it's a straight side view,the two pipes are parallel.So it appears as ONE pipe.The detailed 3d diagram shows the two pipes...connected further down. on the 2008 Hayabusa pic in the CheapcycleParts site fiche.

One is marked # 31(breather),the other,#29...drain hose.See how they're oriented?Those two are pointing forward.They connect to those nipples under there(pic).The is that one short hose,pointing to the right side,with a connector(three-way).Two inlets on top,one pipe going down.#29 is NOT connected to that other three way.It's coming off of the left nipple on your bike.The drain hose.

The BREATHER hose fitting length is SHORTER than the Drain hose fitting...see that in that diagram on the website?SOOOOO....that yellow hose goes INTO the smaller hole.(which is the RIGHT side fitting)...your pic there of your tank is a left side view,yes?The hose goes into that smaller hole...it may or may not slip into that factory hose...you can try and see.You may have to cut it down so a small amount will mate into the factory hose,IDK.I wouldn't try wrapping it around under there anywhere...like that guy suggested?

Your top picture is correct.If it feeds down that line...that's good.

* Last updated by: Grn14 on 6/6/2015 @ 11:46 PM *

Hub says..."3 Holes Think"...it doesn't have three.Only two into one..from what I see in the parts diagram online.

I'm not going to look at the book. I am going to find 11 holes... think.

____________________________________________________________________________________________________
Ho~1-2 = Water hole at the tank and drain tube hole = 2.
Ho~3-4-5 = Y tube inside the tank has the hole at the top of the tank, the end of the tank, the Y tied in for the other opening of that internal hose = 3.
Ho~6 = The large gas filler hole is = 1.
Ho~7 = fuel pump or the hole out the pump's feed pipe = 1.
Ho~8 = #4 cylinder vapor dump hose.
Ho~9 = #3 cylinder vapor pump hose.
Ho~10 = The aftmkt vent tube hole off the housing.
Ho~11 = The gas cap vent hole in the housing.

These are my basic holes to think about. Now I add throttle body cylinders and those hoses attached. I can leave those hoses on, or lighten the load and remove, cap the throttle body nipples off with the rubber stoppers the other 2 cylinders that are not in [vacuum] play.

The Holes________________________________________
Ho~1-2 = Leave open at both ends.
Ho~3-4-5 = Close the top right hole, close the gas tank hole at the back of the tank is that tube. Golf tee the hose that you pulled the rubber hose off. Why? This is open [hole] to a cylinder so lean or stall is the cause if not plugging up that (8th hole) you need to think out are 11 holes, now think.
Ho~6 = Do not close this hole for obvious reasons... think.
Ho~7 = Do not close this nipple for obvious reasons... think.
Ho~8 = Close down the rubber tube off the back of the tank or lean/stall will occur.
Ho~9 = Close down the purge pump at the other throttle body cylinder and disable the pump.
Ho~10 = Do not close this tube at the aftmkt housing.
Ho~11 = Keep this vent hole clean is the thought process.

If I now look at 5 holes and think like this:

1. Left tank hole = The water drain is keep both ends open.
2. Right tank hole = Close this hole or gas sloshes up this hole, dirt enters, I no longer need this vent.
3. Center tank filler hole = The obvious hole is do nothing.
4. Tank housing vent tub = Do nothing as in golf tee that vent tube hole.
5. Aftmkt gas cap = Do nothing is this cap has a vent. The housing has a vent. The tank and tubes are capped off for leaks to the throttle body.

The tank is now a standard old style gas tank with one filler hole and one petcock hole.

---

Exactly my thoughtsLOL

"3. Center tank filler hole = The obvious hole is do nothing".WRONG...this allows nice overfills which keep that line nicely cleaned;)

* Last updated by: Grn14 on 6/7/2015 @ 8:19 AM *

"WRONG...this allows..."

That's the problem thinking this out. What do you mean wrong? It's the same as saying, do nothing covering that toilet bowl. Wrong? Okay, close the lid over the toilet bowl, sit down and take a shit. Why did you cover the main hole... Wrong? LOL!!!

---

ROFFLMFAO!!

Grn, I looked at the cheapcycleparts diagram and the 2 hoses ( both marked #31, hose breather NO.2) are connected into one at the main breather hose(#29, hose, breather). One of those lesser breathers goes to the filler neck. The other, I have no idea -- I suspect it is a backup to the fuel tank in case the filler neck breather clogs. the breather starts from two holes and links up to one main tube. We'd have to tear the fuel tank apart to find that out for sure where the other lesser hose connects but for sure, one of them goes to the fuel filler neck. That's what the gromet on the OEM cap is for.

So, 31 goes to the vent hole. 27 goes to the water drain hole.

You are absolutely correct about the length/depth of the breather hose v the water drain hose. The yellow tube goes down the drain hole a few inches farther. Your pic (viewed from LH side, front of tank points left) shows that he water drain hose is longer than the breather.

SOOOOO....that yellow hose goes INTO the smaller hole.(which is the RIGHT side fitting)...your pic there of your tank is a left side view,yes?

You may be getting your terminology misconstrued (in the text you wrote just before the quoted statement) but your concept is right. The small hole to the RH side of the gas cap ring recess. First pic I posted in the OP. It's the breather hole. It also expels (rather redirects to the T-bodies) fuel overflows and vapors. The yellow tube will not go down as far as it does in the water drain hole but it fits snug in the vent hole. I don't think it will be necessary to press the yellow tube into the OEM hose but I will try. I could snip the tube shorter so as to have less looped back and forth under the ring but I probably won't bother with that. I might need the extra length to properly fit the gasket to the cap and install it. If it aint broke, don't fix it.

Hub, I'm going to have to sit down and ruminate on that 11 holes soon (you mentioned a golf tee, too didn't you?). Kids are still here. Soccer game this afternoon. Wrenching tonight! Also have a lil sketch of the gas cap/fuel tank filler neck I will clean up in Illustartor. We need a concise wrap up to this. LOL no one will be able to follow this thread except us (sorta) three guys!

* Last updated by: Rook on 6/7/2015 @ 9:35 AM *

---

Man, they should have this thread on hayabusa dot org!

---

At least ya got to post that diagram;)That's the one I was trying to do...somehow,someway,the 'copy' wouldn't get the whole diagram...WTF?Never had THAT happen before.

"The yellow tube will not go down as far as it does in the water drain hole"...yep...cause that 3 way coupling is stopping it.

* Last updated by: Grn14 on 6/7/2015 @ 9:54 AM *

That's ok though. It goes down far enough. A couple inches.

Here's my lil illo of the gas cap and what the holes do

MAn that's embarrassing when you have to go to the competition to get tech advice. Good job gents!

This is viewed from the rear, BTW. LH is on left, RH is on right.

* Last updated by: Rook on 6/7/2015 @ 11:44 AM *

---