Carbs, carbs, what the heck is wrong with these carbs

[79XS11F]

I still have not been able to get the needle valves on these carbs to seal when filled with fuel. I have at this point tried .. new OEM needle valves, new rubber tipped needle valves with and with out the little float tab holders in place, Fiber and metal washers under the valves, plastic floats, brass floats. I have tried every combination I can think of with no luck. I can get them to seal dry no problem by applying air or a vacuum to the fuel supply line with the carbs upside down on the bench, but when fuel is added for a fuel level test they will not seal. Even if I bend the tab on the float so far that it is well out of spec, no luck. It just does not make any sense.
Rob

[egsols]

Hey Rob,

Which carbs are you using....79's or 80's? I had the same problem with my 79.

I switched to the viton tipped needles from the 920 virago and adjusted the float height. Seems to work.

I think I posted my specs a while back....I'll search for the link and post it.

Ernie

[egsols]

Hi Rob,

Have a look at this thread and see if it helps.

Ernie

http://www.xs11.com/forum/showthread...t=viton&page=2

[81xsproject]

I doubt it's the issue, but it might be worth trying those valves without the washer and use fuel tape instead. Also, have you double checked that the floats themselves are leak free and moving freely?

[BA80]

That's what I was thinkin' too Jessie. The floats hangin' on the gaskets.

However, when I did my carbs (I have 79 carbs on my SG) I did have a little problem with that for a while too. After running it a while it went away.

[79XS11F]

These are 79 carbs.
The plastic type floats are actually a foam of some sort so they can't take on fuel like the hollow brass floats can. The floats do not appear to be hanging up on the gaskets. I measured it out and they can't get close enough to contact the gaskets. The floats do work smoothly. Tapping on the bowls while filling also does not help at all. I am beginning to think there might be a crack somewhere in the body between the fuel supply tunnel and the bowl but if that was the case I would not get a seal when dry ether.
Rob

[BA80]

79s had the brass float.

Is it just one flooding or all of them?

[79XS11F]

79s had the brass float.

Is it just one flooding or all of them?

I have the original brass floats but had changed them out to the plastic type when I restored the bike. I have not even checked 1 & 3 because I am stuck on trying to get 3 & 4 working. I don't know which one of the two is causing the issue because they are connected as pairs and still on the rack.
Rob

[BA80]

I've never switched floats myself but I've read some threads where those who had had to trim the plastic floats so they wouldn't hang in the older bodies because the older carbs are configured differently just enough to cause problems.

IIRC it was at the far ends, furthest from the valve. you might want to do a search.

JAT

[egsols]

When you changed the needles did you use new seats? The OEM valves and seats could sometimes be fixed with a little lapping compound but I found the last sets I bought to be crap...that's why I went with viton tipped with new seats. A clogged vent can also cause overflow but only when they are in use on the bike.

[DGXSER]

Not sure if you stated this yet or not Rob, but did you change to the XV920 valve seats as well as the vlaves? Those viton tipped valves are just different enough than the stock ones that they can get cocked in the seat and hang up.

[79XS11F]

When you changed the needles did you use new seats? The OEM valves and seats could sometimes be fixed with a little lapping compound but I found the last sets I bought to be crap...that's why I went with viton tipped with new seats. A clogged vent can also cause overflow but only when they are in use on the bike.

Yes, new valves and seats in both cases for the OEM and viton setups.

[79XS11F]

Not sure if you stated this yet or not Rob, but did you change to the XV920 valve seats as well as the vlaves? Those viton tipped valves are just different enough than the stock ones that they can get cocked in the seat and hang up.

Yes.
Now do keep in mind that this bike had run flawlessly for the 3 previous years. This carb flooding issue just cropped up out of the blue this year. I am thinking that perhaps after 3 years it's time to do a full cleaning again. If that is what is needed I will buy an ultra sonic cleaner and do them over the winter.
Rob

[cywelchjr]

Did you make sure the vent lines are clear? As I mentioned to someone else, the symptoms sound like the vent lines are clogged, like something got into a vent link a plugged it up, which would make it do what you report, and it doesn't have to be on the bike if the line is clogged, the "on the bike" issue is if it's the vent lines that are causing the problem when they get hooked up on the bike. I'd suggest trying to blow into the vent lines and make sure that air is blowing into BOTH the carbs when you do it.

[79XS11F]

Did you make sure the vent lines are clear? As I mentioned to someone else, the symptoms sound like the vent lines are clogged, like something got into a vent link a plugged it up, which would make it do what you report, and it doesn't have to be on the bike if the line is clogged, the "on the bike" issue is if it's the vent lines that are causing the problem when they get hooked up on the bike. I'd suggest trying to blow into the vent lines and make sure that air is blowing into BOTH the carbs when you do it.

Yes, vent lines are clear. It was the first thing I checked cause I've been there / done that in the past when I first got this bike.
This is why I am stumped on this one. I am sure I have checked everything a few times now with no luck. I just wanted to sort it out long enough to squeeze in a few runs before it gets real cold out.
Rob