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[Riddle]

Ok I don't know where to start.. #3 carb is over flowing from air vent so I cleaned the needle and seat, adjusted float hieght and managed to stop the leak for about 5 min. I went in and cleaned all the carbs iternal parts with the dip system reasembled and #3 leaked again. I tried the bench test and blew air thru the gas line while the carbs where upside down and seemed to work... Hooked it back up to the bike and turned petcock to prime, out came the gas. no leak when in on postion so I choked it and fired her up, the rpm shot staight to 5k. Tried bread-tie method to sync um but I felt like I failed.. Any advice would be inspiring to try again. Thanks xs11 community

[DGXSER]

With the petcock on prime, try tapping on the float bowl of no 3 to see if the float closes then. They can get stuck on the side of the bowl or the gasket, sometimes tapping will break it free. Otherwise, pull the carbs, look at the gasket to the float bowl and trim it to match the float bowl on the sides, so nothing hangs over to catch the float. You need to resolve the float issue. The reason it does not leak in on position is no fuel flows in on position until the bike is running. But when it does run, no 3 will flood and burn very rich.

As I suggested in your other thread, get at least one vacuum gage and use the PVC pipe to deaden the bounce as shown in the tech tips and synch the carbs by gage reading.

[81xsproject]

A set of new float valves is cheap. If you have a 70 bike, looking into the float valve conversion. Then move on to your petcocks if they are not closing off the fuel supply.

[psycoreefer]

I agree, first step is stop the leak, another member had a bad fire because of a leak like yours, be careful and keep and extinguisher handy just in case.

You tried cleaning so I'd say its time to step up and replace the float valve seats and needles, that should solve the problem as long as your floats aren't stuck on anything.

Bread tie sink is only a starting point, you'll need a vacuum gauge or carb tune or something to get a real synch on those carbs.

[dbeardslee]

tried the bench test and blew air thru the gas line while the carbs where upside down

I hope you didn't do that with the bowls attached. The 78 carbs have brass floats, and applying air pressure to the fuel or vent lines with the bowls in place will increase the air pressure inside the bowls and squish your floats. If that did happen, you can 're-inflate' them with a brake power bleeder.

[Riddle]

I only blew it with my lungs .....

[dbeardslee]

Unless you've got the lung capacity of a sherpa, they're probably alright .

[Riddle]

Cool I was starting to think f** something up

[dbeardslee]

The other thing to keep in mind is that putting air on the vent lines will usually get something more stuck, if there's something in there. Best way is to take the bowls off, and blow it out from the inside - with an air compressor . A plugged vent will cause carbs to overflow.

[Riddle]

how do u tell if if u have A clogged vent? Is there anything else that would cause the carb to overflow besides float or needle seat.. I ' ve the seat over and over and can't figure it out

[dbeardslee]

The other end of the vent exits through a small orifice in the bowl flange. Shoot a little carb cleaner in the orifice, and blow it out from the flange side first. Then if you put compressed air on the vent line (with both bowls removed) you should feel a pretty energetic stream of air. Also, make sure your bowl gasket hasn't deteriorated to the point that it's plugging the vent. There's also a tiny little hole at the bottom of the slender brass tube that sticks up out of the bowl flange that also needs to be clear of restrictions. I don't think that would make them overflow but it will affect your enricher circuit. As long as your in there you might want to make sure that the bowl gasket isn't sealing that hole.

[Riddle]

The gas is leakin out of all the holes excerpt long one at the top... So I don't think there's a clog.

[DGXSER]

I had a continual issue with leaking float needle valves a while ago. I would clean the carbs, check the float seal before I put the bowl on. So the Prom suggested bench test with bowl off and with bowl on upside right. Everytime it would hold fine. But everytime I put the carbs on the bike I got a leaker!! I was seeing all kinds of colors and ready to push the stupid machine down a hill and light it on fire!!! Then I noticed a very small piece of black rubber in the screen of the floats. I was using automotive style fuel line with the soft rubber inside lining. The barbs on the fuel Ts were chafing off pieces of rubber when I put the lines on and that would get into the floats and cause one to leak. JAT

[Riddle]

I have screens over the needle seat.. I'm guna check that still. WhAt type of hose di you replace with?

[DGXSER]

I found some yellow vinyl type hose made by Briggs and Stratton for lawn mower engines at my local hardware store. It has held up fine for over a year now.