Leaking Carbs

[jfb130]

OK. I am losing my mind. I recently replaced my carbs on a 1980 XS110. The old carbs on it had 2 inlets for fuel, the new set (from Neandrathal Cycle Salvage) has 4 inlets for fuel. Can I just hook up a splitter to feed all four? Secondly, when I start the motercycle with both the old and new carbs, I have the same problem. Fuel rushes from the area where the air filters connect. It's happening no matter which set of carbs I use. Can someone please help me out on this I really don't understand why or how to fix this problem. I cleaned my old carbs and the problem continued then I purchased these new/used ones that had been cleaned and the same problem.

[skids]

Re: Leaking Carbs

They probably gave you a set of carbs from a 78 or a 79 xs11. There are not 4 inlets for fuel in the older carbs. The top inlets are for the plastic tees (goes between pairs of carbs) that are hooked to vacuum hoses which hook on to the two nipples on the air box. The bottom holes are for the fuel tees (goes between pairs of carbs) that feed fuel to the carbs. The holes on the outsides of the carb pairs are not drilled through into the carbs. If you use the older carbs with the newer airbox, you might want to drill out the nipples on the air box so that the hoses will draw vacuum. You can not hook the hoses to those nipples if they are filled with plastic or the carbs will continue flooding.

Originally posted by jfb130
OK. I am losing my mind. I recently replaced my carbs on a 1980 XS110. The old carbs on it had 2 inlets for fuel, the new set (from Neandrathal Cycle Salvage) has 4 inlets for fuel. Can I just hook up a splitter to feed all four

[Ken Talbot]

Technically, the hoses from the upper Ts to the airbox nipples are not really vacuum hoses, they function as atmospheric vents for the float bowls. Other than that, Sid's got it right. You wouldn't want to get confused and connect them to the vacuum nipples on the carb manifolds

[jfb130]

Another Question

I do not have an airbox on the bike. The prior owner replaced it with individual air filters. Where would I run the top lines to if I don't have an airbox. Also, do you think not having an airbox would cause my carbs to leak gas from the holes in the back? My real problem is that gas runs from the carbs even if it's running. Any ideas?

[Ken Talbot]

With no airbox, you can get away with running the vent hoses up under the tank somewhere where they're out of the way yet still venting. Some guys install a small filter in the end of the hose to keep dirt or bugs out.

Not having an airbox will not cause your carbs to leak. Gas can only run out those holes if its level is higher than what it is supposed to be in the float bowls. That can be caused by a few things such as:
- inoperative float valves due to damaged needles and/or seats
- dirt between needles and seats
- floats that sink
- float height not set properly
- fuel being supplied through the upper Ts

Have you had a chance yet to plumb the fuel Ts and the vent Ts correctly to see if you've still got gas leaking out the carbs?

[skids]

I wonder if I can measure the vacuum with a magnehelic gage, at say 5000 rpms and report back, Ken? :-) OK, OK, they are called vent hoses, but they will show a slight vacuum. Wanna bet?

Originally posted by Ken Talbot
Technically, the hoses from the upper Ts to the airbox nipples are not really vacuum hoses, they function as atmospheric vents for the float bowls. Other than that, Sid's got it right. You wouldn't want to get confused and connect them to the vacuum nipples on the carb manifolds

[skids]

No, WAIT! Ken, you are on to something! A new way for xs11 fuel injection! I like it!

Originally posted by Ken Talbot
You wouldn't want to get confused and connect them to the vacuum nipples on the carb manifolds

[Ken Talbot]

Me bet with someone who uses language like magnehelic gauge in a family oriented forum - you're on! I'll go a beer on it. Of course, we'll have to settle at the meet in Montana (hey, maybe a catchy logo for a T-shirt) this summer...