I'm thinking of Shooting my carburetors!

[lsippell]

I'm thinking of shooting my carburetors!

I put them on the bike, and occasionally, #3 and #4 will overflow. Put them on the bench, and I have not yet found a way to make them take in a bit more fuel than there suppose to.

I was syncing them today, and after about 5 minuets of running they started to overflow. Shut down. Turned the fuel off. Said a few choice words. Turned the fuel on and started it up and not a sign of overflowing for the next 20 minuets. An hour or so later, took it for about a 10 mile run (strong performance from 1000 to 8000 rpms, no flat spots) pulling into my yard and got a strong smell of fuel, looked down and saw fuel running down the side of the engine case. Parked, shut it down and turned the feel off. Turned it back on to prime and not a sign of overflowing.
The tank is freshly epoxy lined, two fuel filters (clear) in the lines going directly to the carbs. In the 4 or dozen times I pulled the bowls off there has not been a sign of trash in the fuel, New needles and seats (and o-rings). I am about at my wits end. Swiftly loosing patiently and considering borrowing my sons 44 Magnum Desert Eagle to put the carbs out of my misery!

Louis

[Ken Talbot]

Did you catch the note the other day from Mike F about carb floats sticking ?

[tab1324]

float valve height

I'd check the float height and make sure you're not boardering such a rich position that the needle valve doesn't get good pressure to close. Make sure they're all (4) the same.

Tom B.

[SG-Olli]

Maybe

a friend of mine from the XS650 forum had something similar. The side of the floats were touching the side of the bowl so sometimes the float got stuck and the carb overflowed. When he carefully bent the floats to their proper width everything was fine again.

[lsippell]

I read the thread on the carb floats sticking. The fuel level in all 4 carbs are set to 3mm below the float bowl screw flang (+- .5 mm). Non of the floats are touching the bowl. When I first assembled the carbs #2 was occasionally floding while it was still on the test jig. It's float was toching the far side of the bowl. After catching that, I checked all of them for clearance, even trimed the aftermarket gaskets on the inside where they overhung.

Louis

[TopCatGr58]

Hey Louis,

Part of what that thread showed was that the needle valve can sometimes drop down too far, and get slightly turned at the opening of the valve seat, and get's stuck, and so the float can't push it back in! SO...the float arm opposite of the needle may need to be bent so that the floats DON'T drop down too far allowing the needle to ONLY come out so far from the valve seat!

Try pulling the bowls off, hang the carbs right side up, and see how far down the floats drop...and if the needle valve comes out so far that it might get turned, stuck??

It's not just a matter of the floats rubbing against the bowl sides!
Good Luck! T.C.

[lsippell]

T.C. When I read that thread, my carbs were sitting on the bench, ready for me to install them the next morning. Needless to say, the bowls came off the carbs to check for that before I installed them.

I went out this evening and turned the fuel on and fired it up, after about 10 seconds, # 3 started overflowing, but #4 didn't. Oh well, off they come in the morning.

What really upsets me is that I cleaned them 3 times before installing them to avoid having to pull them again. Well I guess I've succeeded in getting them clean, cause it runs great, even when one or two of them are overflowing.

Louis

[prometheus578]

Was a recent thread on plugged or kinked float bowl vent lines. They can cause mysterious overflowing, too.

[81xsproject]

if the 82XJ is anything like the 81XS he may not have vents.

[DiverRay]

He has vents, just not the vent hose. The vents Must be clear or clean, as you can have a problem with vacume or pressure in the carb. a bit of dirt, bug, or road junk could plug the XJ vent. I don't know the newer carbs, as I ride a '79 standard.
If the vent of the card is near the air horn, and you are running "pods", make sure none of the holes are blocked!
Ray

[tab1324]

float needles

If you wanna try replacing needles I have a couple extra (unused) I could send you.

Tom B.

[lsippell]

I appreciate the offer of needles, but all mine are new and look perfect under magnification as well as the seats. They seal with their own weight (upside down and no floats, just the needles).

I'm pulling them off again in the morning, though I don't know why. They never over flow on the test jig!

I have even had them on the bench, full of fuel and took the fuel line off the coffee can/fuel tank and put a blower against the fuel line with 125 psi blowing into the carb, and the needles haven't unseated. The needles also won't unseat with the carbs upside down and only the weight of the floats holding the needles closed.

Louis

[lsippell]

I feel like an idiot!

I feel like an idiot!

My carbs, that only overflows when on the bike (key phrase ‘only on the bike) but never on the bench are now fixed!

After puling them three times, and spending a lot of hours messing with the floats and needles, I put them back on late this afternoon, hooked everything up. Turned on the petcocks and after about 20 seconds watched the gas dripping off # 3 and 4. I still had the tank propped up at the back, and happened to notice that the intake boots for 3 and 4 were wet with fuel almost to the top of them. Now, I have small fuel filters sitting between 1 and 2, and 3 and 4. I immediately thought that a connection was leaking so I pulled the line off the carbs and the octopus to check. It turns out that the fuel filter has a hole so small; it will only leak when there’s pressure from the weight of fuel in the tank. Turn the petcocks off and the filter will sit there from now on full of fuel, but turn that prime on fuel shoots out of it in a very tiny stream! The hole is not in the seam, but right above it and so small it’s not visible with a 30X magnifying lens.

Louis

[don07tncav]

Mystery solved!! It's great you found the problem at last!

[Ken Talbot]

Now that's not one I've come across before. Bit of a PITA for sure, but just think how much better you are now at getting those carbs off and back on...