carb tees

[Texas Rookie]

I have the carb bank out of my 79xs11 standard and right before install (and after carb part soak and reinstall) I thought I would check to see if the float valves were holding. Turned the carbs over and blew threw the gas supply lines. If floats are holding shouldn't be able to blow much. Much to my chagrin I can hear air hissing out of what appears to the the carb tee fittings. a couple are slightly stiff to rotate but the other two are relatively easy to rotate along their axis's (axii?). My question is will the o-rings fatten up with gas (carbs sat dry for years) or do I need to replace the tees before I try to start the motor for the first time.

Any other helpful hints on start-up.

Also, Pulled the plugs and #4 was black with carbon (others had tan ceramics and appeared to be fairly clean). Again these have been in the bike for many,many years.

[DiverRay]

I'll start at the end of your list.
The NEW plugs should be fine. If you rebuilt the carbs, and at least replaced the needles and seats, you should NOT have any black plugs.
The "T" was built with a rubber coating over the pot metal for the seal. I have one or two that the rubber is gone, and they will NOT seal. I think someone had posted about a new "T" that will fit. try searching on "fuel inlet" or "T", and see what comes up. If the rubber is gone, or split, try removing it and locating a small diameter o-ring to replace the rubber seal. I would think two per side, with a little silicone grease to help them on, would hold. The problem may be in finding an o-ring with only a 1mm thickness, and 8mm diameter. A 3/8" is very close to 8mm, if that helps with the search.

[Larrym]

Had a similar Leaking fuel Tee problem with my Test Carb bank. When I did mount them up and turn on the fuel petcocks it was only a few seconds before a drip turned into a stream of flammable liquid. Had already placed rags underneath carbs just in case.

Luckie Eddie found some aftermarket tees that are working for him. See this thread:

http://www.xs11.com/forum/showthread...rfect+fuel+tee

Important to note that at the bottom of the page/link for Eddies Tees there are Two sizes/widths. When I break my carbs apart I'll know which size I have and will order the right ones.

[prometheus578]

"That really blows."

Blowing through a fuel line is no way to check for anything.
Imagine the fun you would have had... had you not heard the hissing and installed the carbs without properly testing them.

Anytime one does carb work, one always bench-tests the carbs by hooking fuel to them and letting them sit for a while.
Leaks, whether at "T"s or "needle and seat" areas will soon become evident.
Much more evident... than trying to see air "leak" past a worn float needle.
And when you do hook a fuel line to the carbs to check them, you need to "BLIP" the float to clear the air from the fuel line. Then, dry the area with compressed air(or paper towels) and sit, wait and watch.

[Larrym]

Abundant Blips

Understood everything about Prometheus's reply except for the "Blip". I pictured the carbs assembled and right side up so I couldn't fathom what "blipping" was or how to do it.

Took a chance and entered "blip" into site's search engine. Blips everywhere in threads. Found out that "Prometheus Blip" refers to carbs upside down with float bowls removed. "Blipping" allows anyone to not only detect a leak but also to see where the fuel is coming from. Superb technique that I'll be copying.

Thanks Prom!

(The Greek gods did not do Everything for the mortal man and thus rob him of the glory or shame he could earn for himself.)

[fredintoon]

- - small diameter o-ring to replace the rubber seal. I would think two per side, with a little silicone grease to help them on, would hold. The problem may be in finding an o-ring with only a 1mm thickness, and 8mm diameter. A 3/8" is very close to 8mm, if that helps with the search.

Hi Ray,
thats a reasonable salvage if a replacement tee can't be found but I do have one caveat, 3/8" equals 9.525mm. The nearest inch size to 8mm is 5/16" which is 7.9375mm.

[prometheus578]

Thanks, Larry... you've sort of have the right idea.

When one hooks up an auxillary fuel source to check the carbs, they often forget that the fuel line hasn't any fuel in it... yet.
So they sit and watch their up-side-down carbs for five minutes...see no fuel leaks and think everything is hunky-dory(whatever that means).
Truth is, that it's gonna take ten minutes for the fuel to move down the line... as the air slowly leaks past the leaking... needle valve, or whatever.

Carbs up-side-down... "Blip" the floats to clear the air from the lines... dry up the spilt fuel that came out... and then watch.

[Texas Rookie]

Hey Prom,

The blow-through-the-fuel tube trick was obviously a very crude test method to determine if there were any overt problems, as indeed there were.

I found some fuel injection o-rings at the auto parts store that look like they will work to provide a solid seal on the tees. After peeling off some of the rubber coating on the part of the tee that goes into the carb body (leaving enough to provide a backstop of sorts for the 2 o-rings per tee side) and applying the tiniest bit of grease) they slid in and seem to provide a very snug fit.

Will test (via blipping) sometime over the course of the next week and report results.

Thanks to all of you on this board for your suggestions and techniques on this and other mechanical matters.

[prometheus578]

Just so there's no confusion...
"Blipping" is not the test.
The test is to see if fuel leaks past the needle and seat.
Blipping consists of nothing more that raising the float so that the needle leaves the seat and allows the air in the fuel line to escape and the fuel to reach the seat area.
One then dries the seat area and watchs for more fuel to come out.

The weight of the floats hold the needle down in the seat... same as they would do if the carbs were right-side-up and the rising fuel level were acting on the floats.
Also, sometimes when lifting the float, the needle will remain, due to that thing called gravity, in the seat not allowing air/fuel to escape when trying to bleed the line. Tap the needle with something like a dental pick or a thin screwdriver to dislodge it.

[TopCatGr58]

A tech tip in the making!

I found some fuel injection o-rings at the auto parts store that look like they will work to provide a solid seal on the tees. After peeling off some of the rubber coating on the part of the tee that goes into the carb body (leaving enough to provide a backstop of sorts for the 2 o-rings per tee side) and applying the tiniest bit of grease) they slid in and seem to provide a very snug fit.

Thanks to all of you on this board for your suggestions and techniques on this and other mechanical matters.

Hey Tex,

Now's your chance to share the wealth! How about taking a few photos of your Tee's with the rubber trimmed back, the Orings in place, and the INFO on the exact model/size of the O-rings, so that a TECH TIP could become of this!!
T.C.

[Texas Rookie]

will do on the pics "C"at

Don't know the exact size on the o-rings as I had to buy an assortment kit (about 7 bucks, approx 170 pcs) that has 2 sizes (the smallest 2) that seem to work. I'm using the bigger of the two as they seem to provide a tighter seal but again I am still in the testing stages. More info to follow as I get time to work on it (probably this weekend).

[Larrym]

My haste...My waste.

Definitely want to see your O-ring solution to this problem, TR. I have 4 carbs ready to be joined at the hip and the new fuel Tees haven't arrived from Motorcyclecarbs.com. ($40 each!!)

In the meantime I decided to do a little R+D myself. Here's a pic of the original Tee and the one I shaved off the "rubber."



found a piece of fuel line lying around...



cut off about 1/2 inch.....



chucked a 1/4 drillbit into the drill press, slid the section onto the shank of the drill, used a combination of jeweler's files (triangle and flat), and voila!!



seems like a good start??



Sort of like the original???



I test fit it into the fuel inlets and it "feels" like won't leak. If my new Tees don't arrive tomorrow I just may jump the gun, make up some more of these, and join all the carbs together. At least for "leak test" purposes....

Sorry for the fuzzy pics. Umm...the girlfriend has the good camera.

[randy]

FYI, those in the photos are the vent tees, the fuel tees are the ones with the longer stems.

[Larrym]

TEE and tee

thanks Randy,

Both Tees in this R+D process were installed as fuel inlet Tees in a bank of carbs I took apart. Only one of these Tees were leaking. In another set of carbs I took apart the longer Tees were used in the fuel inlets. Both of them leaked.

see this thread:

http://www.xs11.com/forum/showthread.php?t=20455

As the longer ones leaked I'll use them as raw material for the R+D and install them in the fuel inlets for the bench leak test.

[Larrym]

Right Tees/Wrong Orifices

Got the "Tees" today from motorcyclecarbs.com. They look like this:



They are the perfect replacements for the carb bowl vent Tees. Un fortunately it is the fuel inlet Tees that were leaking on my test bank. Sure, I could have installed them in the fuel inlets and then did a bench leak test. ( But NOooo....)

Since I was already tooled up and had the old fuel Tees as raw material....



and like a magic trick...



I know I could just order the correct fuel inlet Tees at $40 each and then be through but I just had to see if this method would work. I have joined the carbs together and will "Blip" the floats tomorrow after I set up a fuel tank. If the Tees leak then I'll let all know that this was a very bad idea and humbly get my credit card out again....