Testing flooding carbs

[janwic]

Hi all,

I bought my XS1100F a couple of months ago, I got it cheap as it
did not run well in the range from just above idle until about a quarter of full throttle. The previous owner dismantled the carbs, had someone clean them but failed to get the bike running right. Having read other posts in this forum made me suspect that there might be trouble with the float valves. However, it turned out to be difficult to measure the different levels around the floats as my bike is equipped with float bowls with plain bolts (no nipples), nothing to attach those clever tubes you guys use to measure the adjustment of the floats.

So I thought that I might be able to at least check that the float valves manage to close the fuel supply by removing the bowls, closing the float valves by hand and then opening the fuel lines. The result of this experiment? Me experiencing fuel running down the shirt sleeves while I'm shouting "shut off! shut off!" to my daughter who was on petcock detail, that's what happened. It seems that all four carbs gushed despite me keeping the floats at top level. Now for my question, are there any other routes for fuel to enter the carburettors apart from the float valves, or was this a successful test setup? Since it's strange that all four floats should fail at once, is there a faulty way to assemble the carbs that would make them behave like this?

Regarding the bolt in the bowls, a post said that bleeder nipples might fit. Now, the float bowl bolts on my bike seem to be UNF 5/16, not M8, is that correct? Seems strange that the Japs wouldn't use metric bolts...

Regards,

/Jan

[DiverRay]

M8 and UNF 5/16 are VERY close. The floats are M8, as there are NO US bolts on the XS1100.
I would think about removing the carb banks, and ordering new needles and seats for the carbs. make sure yu replace the gasket between the seat and the carb body. You could check for the gasket, as the PO may have left them out?
If he did, you should be able to get new fiber washers at good parts store. I think they are 12mm, but can't remember exactly. with the carbs off, set ALL the floats too the same height, about 26mm from the highest part of the float to the float bowl gasket. You can then hook up the fuel tank, and keeping the carbs upside down, turn on ONE petcock at a time. You should NOT have any fuel leak as long as the carbs are upside down. If you do, try to see if it's from the needle or if it's leaking past the seat. That should be the ONLY place fuel is leaking.
The last thing to check for is that the fuel lines have been connected to the fuel inlet fitting. There are two "T"'s on the '78-'79 carbs. The lower rear one is for the fuel, and the upper one, closer to the center of the carb body is for the vent. Be sure the PO didn't hook up the fuel to the vent!
Good luck, and let us know how it works.
Ray

[prometheus578]

DiverRay

26mm from the highest part of the float to the float bowl gasket

I'm not in the habit of questioning another's advice, but did you mean to type "... to the float bowl gasket mating surface"? (not to the gasket itself)
http://www.xs11.com/forum/showthread...5&pagenumber=1

[TopCatGr58]

What Diverray has said is good, and the wrong inlet "T's" is what I was thinking also! IF the upper vent T's are not vented, the bike will not run properly!! Also, not sure what brand of carb parts and kits were available to the P.O. in Sweden, but if they contained the K&L parts, that can also be a problem with the low end rpm behavior....those jets are notorious for being WRONG and too rich! Get some real Mikuni Pilot jets, and with the above mentioned tips, you should be able to get working quite well!
T.C.

[skids]

To check for leaks, you can blow into the fuel hoses with the bowls off and the carbs upside down. If you repeat your other methods, at least give your daughter a fire extinguisher to put you out!!! :-)

[janwic]

Gentlemen, you have made me so much happier; the fuel lines are infact currently connected to the upper 'T's while the lower ones are connected to the vent tubes. I'll swap them and report the results.

[janwic]

Here's my garage report:
Exchanged the tubes for the two sets of t's so that the lower ones receive the fuel
Mounted the carbs on the bike, watched it flood out of one vent hose (foolishly did not record which one)
Disassembled the carbs again, realized that the t's are not of equal length, assembled and mounted again, went to bed.
Wife woke me up at 3 am because of whole house stinking of fuel, realized it is a bad idea to leave the petcocks in 'prime', spent the day cleaning garage floor, ventilating the house and maintaining a rather bad temper.
Mounted the carbs to a setup at my workbench, noticed that the fuel comes from carbs 1 and/or 2, separated carbs 1 and 2, checked again by holding a finger on the end of the t for each carb, found that neither #1 nor #2 flooded. If there is a God, he has humour.
Mounted the carbs to the bike again, no flooding this time. The bike started!!! It still ran ugly though, lots of carbon on the plugs, so I disassembled the carbs again and lowered the needles (raised the washers) a step. Now the bike runs alright but not perfect. There is still work to be done, and I don't mind.

Guys, ever since I bought the XS I have marvelled at the amounts of knowledge put into this forum, and the interest and support of all of you who participate. I have so far failed to find a forum of equal quality for my other bike, a '82 Kawasaki Z1100 Spectre (right now put apart due to a broken head gasket). Comparing my Kawasaki to my XS, and comparing the Kawasaki and the XS community, I realize that my Kawasaki is a piece of engineering, while the XS is more than that. It has a "geist in the machine". Of course, there must be an engineering explanation to why the flooding stopped when the carbs were separated, but I argue that the lack of a Kawasaki forum equalling this one must be because those bikes have more plausible errors, making the bikes becoming more maintainable by us less experienced (or perhaps less intuitive). But then again, maybe I didn't google enough to be able to find such a community. Or did I?

[prometheus578]

KZ Rider is the Kawi site I hit when I have oddball questions. And you are correct... out of all the sites I visit, none is as friendly, informative, nor set up as well as this one. Some of them are just pure hell to try to move around in and find answers.

[GNEPIG]

.. ditto here, ..yeah, what prometheus said
there's no place like home
there's no place like home

[skids]

SOmetimes a piece of crud can get stuck and hold the needle away from the seat in the fuel valve and it can get flushed out (self healing carbs),

I had a fuel tee from bike that had no fuel in it for years that leaked at the tee/carb connection, but it soaked with gas and began to seal (I think),

I know that the float pivit pin can get corroded and if the floats don't rotate freely, the problem can be intermittant,

I had a fuel valve needle that had a sticking spring-pin. I believe that could also be an intermittant thing....