What now?!

[dbeardslee]

I just rebuilt my carbs (again) as I was getting gas leaking out of all four when the petcocks are on. Figured the needles and seats were acting up, and I could see a distinct ring around all four. I put in new needle and seats, as well as new slide needles, new gaskets, and new-old plastic floats (set to 23mm). Didn't touch the jets. Anyway, I just mounted 'em and I'm getting the same thing. Turn the petcocks on and gas comes pouring out the carbs. If I shut them off with the bowls full she'll start right up, but if I turn the petcocks back on she starts sputtering and blowing fuel everywhere. As the fuel valves are brand new, I'm at a loss for what to check next. Any ideas?

[Guy_b_g]

May sound stupid, but check to make sure you didn't connect the fuel lines to the carb vents by accident.

[boyat68]

dbeardslee:

The plastic floats fit very closely to the sides and the front of the carb. Sometimes the float falls too far down in the bowl and sticks to the sides or front. The fall of the floats can be controlled by the tang on the back of the hinge. Also the spread of the float bodies (plastic part) may be splayed out sideways a bit and hang on the lip of the gasket. It took me 13 times removing and resetting the floats before I got mine adjusted. I even used the Ken Talbot test apparatus to monitor the leak ability of the floats. They would pass the test overnight and when I put them on the bike they would leak, so off they came again and I would check the fall and scraping of the floats on the side of the bowls adjust and try again. Make sure that each side of the floats are equal.

[dbeardslee]

I always check to make sure the floats are hanging straight. I check them on both sides as well to insure the height is correctly set. I'll check the tangs as these floats are slightly different than the brass.

I'm wondering if I should set them to 25.7mm. as I'm getting gas out of all four carbs. I could see a stuck float being the culpret on one, maybe even two carbs, but not on all four. I've seen conflicting info. on what the correct setting is. Some say 25.7 for brass, and 23 for plastic. Others say it should be set according to the year and model of the bike regardless of whether they're brass or plastic. Anybody know for cetain?

The good news is, with the airbox gone and pods installed, it's not as big a PITA as it used to be.

[tarzan]

I would set them by year and model.Just go by the book.It sure sounds like your floats are too high.The float I had that was crooked and set too high leaked straight to the airbox.Once corrected no more leak.

[The Lorax]

Hey Doug, Had something similar to your issue once,one carb would always leak. as it turns out, somehow or other, the float tang where it wraps around it's hinge pin thing got itself out of round and was sticking on it's pin, I could manually break it free, but it would always get stuck again. ended up pulling the float and running a drill through the tang thing, works good now. I know, I dont know the proper names for any of the stuff in a carb, but you get the point, at least I hope so. let me know if I can help. have a nice day and ride safe

[dbeardslee]

This is really weird. I changed the float height to 25.7, and I'm still gettin' the same thing. I'd put the brass floats back in, but somewhere up the po line somebody must have put compressed air on the fuel lines with the bowls attached, and the result is that their squeezed in on the sides and I don't think they displace as much liquid as they should. I built a little vacuum chamber to try to get them popped back out, but I need a stronger vacuum pump to make it work.

If the fuel valve is the only way for gas to get into the carb, I'll concentrate my efforts there. Is there any other way for gas to get in there? Enricher circuit?

[Ivan]

Are you sure you have the right needle and seat? I have a set of carbs off a 79 I think, and the set on my 81. The needle and seat are different. Although I haven't looked closely, the seat may interchange causing a mismatched one to leak.

If I were in your situation, I would have a tray under the carbs, and pull a bowl off one of the end carbs, and slowly turn the fuel on, carefully watching where the fuel leaks when holding the float up. I wouldn't recommend smoking during this procedure, and don't use your wife's "magic chef" baking dish. Antifreeze flavor never comes out of those, so I am assuming gasoline doesn't either.

[dbeardslee]

Yeah, they're the right ones. I just replaced a set because of the same problem. I think the next thing I'm going to try is putting the brass floats back in. While I've got them off and apart, I think I'll connect them to my auxilliary gas tank and see if I can see where they are leaking - good idea Ivan.

It's weird that when the carbs originally failed, all four of them started leaking at almost the same instant. That's kind of what's making me think it might be something other than the fuel valves. I guess it's possible that all four would wear out at the same point - just seems unlikely.

[TopCatGr58]

Hey DB,

With brass floats caved in, you can try dunking them in almost boiling water, holding them down in the water to get the air to expand inside of them to pop them back out, but also look for bubbles. If bubbles, then they are leaking anyways, and so you wouldn't want to use them, but otherwise you might get lucky!?

Ivan, the 79 uses the screwed in float seats, and the 80-81 uses the pressed in seats, so they can't be mismatched. There was an article by Jesse/81XSProject about using the Viton tipped needles from the XV920 IIRC for the earlier model carbs and seats, the rubber tips do seal more easily than the metal ones! JAT!

And again, as others have inquired, no aspersions to you, but you are connecting them to the LOWER "T" fittings on the carbs right? Also, are the UPPER "T" fittings VENTED properly, not just capped OFF? IF they are capped off, then the carbs WILL LEAK because they can't equalize pressure, so make sure the upper "T"s are vented properly, like carb 1-2 together into a "T" fitting, not just to each other!
T.C.

[bikerphil]

[QUOTE=dbeardslee;181965]

It's weird that when the carbs originally failed, all four of them started leaking at almost the same instant. QUOTE]

Maybe the tank vent is clogged and there is excessive pressure in the tank from sloshing gas. Try it with the cap open. JAT

[prometheus578]

I'll bet he plugged his vent lines.

The good news is, with the airbox gone and pods installed, it's not as big a PITA as it used to be

Dadgummit, T.C.
You beat me by 10 minutes.

[dbeardslee]

As always, thanks for the replies.

I always disconnect the fuel lines from the tank, but leave them connected to the carbs, so those are where they've always been. The vent lines I have tipped with small fuel filters. I removed them earlier to make sure they weren't clogged, and they're fine.

I also took a good look at another carb body I had out in the garage. Where the 't' connector goes in, there's only one orifice and it leads to the float valve, so that's gotta be where the problem is. The valves should stop the fuel flow, but they don't.

I tried boiling the floats last weekend and couldn't get them to pop. I'd like to leave the plastic ones in, but I have a sneaking suspicion that they're the culprits. Everything else I replaced was with parts identical to what came out - the plastic floats are a different variable. I wish I could see what was going on inside the chambers with the bowls secured .

[DiverRay]

Just for fun, try setting the floats REALLY HIGH!! I've had to do that on one set, just to get it running properly. I would also run carb cleaner through the VENT SYSTEM, from the bowls to the filter you have on. I worked on one bike that had a very fine "bubble" of something over a vent inside the bowl, and I could NOT find the reason for the leaking! After blasting everything, and running a Q-tip through the vent system, the carbs worked. HTH

[egsols]

Hi dbeardslee,

I'm assuming you've got 79 carbs. I tried swapping in the plastic floats on my 79 and found that I had to bend the tangs too much to get the right height. With the tangs bent that much it caused the float valves to get cocked in the seats and thus cause leaking.

I had lots of trouble with the aftermarket valves and seats, poor quality IMHO and didn't feel like shelling out close to $200 for ones from the dealer. I ended up using viton tipped valves and seats from a XV920. Those seats come with a steel washer which made them sit higher then the stock ones so I used the fibre washer instead and played with the float height. It didn't take much to get them to overflow. I drilled out a set of grease nipples and replaced the drain plugs with them. I set up the carbs with the grease nipples and clear tubes and got the floats adjusted so that the fuel level was about 3mm below the top of the bowl. This was at 27.7mm for the brass floats. I also made sure that they didn't drop too far, I think they ended up around 31mm at full down.

I still get the odd dump of fuel but that's due to sticking floats. Usually I tap the carbs before I take off. They only seem to stick if the bike has been parked for a while....so I'm assuming that the fuel is drying up in the bowl and causing the floats to stick on the pins. The brass floats don't have the sleeve on their hinge like the plastic ones do.

Hope my ramblings help.