Topic: gas pouring out of #3 carb?

[75 super sport]

freshly rebuilt rack of cabs is spitting fuel out of #3 carb? any ideas? it is coming out of the little fitting on the air intake side.

[bollingball]

What carbs? do you have a pic of said little fitting?

[scondon]

Can you be more specific about which fitting you're referring to?  If the carb is "overflowing" it is likely the gas flow is not being shut off by the float needle i.e. needle not seating or float sticking/adjusted improperly. If it is "leaking" then there is likely a seal/gasket problem.

[75 super sport]

http://i1054.photobucket.com/albums/s492/75supersport/IMG_2511.jpg
 I couldnt get a good pic of the #3 carb, but here is a pic of the #4 carb. The two small fittings at the bottom of the picture
1975 CB750f Stock/ freshly rebuilt carbs.

[bollingball]

Is it not running when it leaks there?

[scondon]

The ones inside the air intake? Those are your air jets for the slow/main fuels circuits. If gas is coming out of these your carb is overflowing/fuel is not shutting off when float rises.

Pop off the float bowl of #3 carb and have a look. You can shut the petcock off and put a pan or bowl under carb to catch gas. Turn on petcock and lift float with your fingers to test that the float needle does in fact shut off the flow as it should.

Pop off #4 float bowl and compare float height to that of #3. Are the floats in the same position when the gas flow stops? This is not the procedure covered in the manual on how to check/adjust float height. It is merely a way of checking things with the carbs still on the bike. Often I have found something simple while doing this that has saved me from yanking the carbs off the bike.

[bollingball]

Also check that the float has no burrs around the pin and post area.

[75 super sport]

Great, Thanks guys. I will let you know what i find a soon as i can.

[Spanner 1]

Gas should come out of the overflow tube before it would appear at the air bleed openings ( the little tubes your referring to ).... so, either the o/flow stand pipe in the bowl is blocked or the drain hose is pinched down by the swingarm... just pull it up and see if you can blow thru' it into the carb bowl. The other cause would be blocked carb vent passage ( it's up in the carb body and opens to atmosphere).... a lot to these carbs isn't there 

[Grabcon]

I am fighting the same issue. I finally have broken down and bought 4 new rebuild kits. I am very tired of screwing with this. It better work. I was not able to closed the float and needle on the bench. The needle and seat are 36+ years I hope they are just shot.

[Stev-o]

The last time one of my carbs leaked it was the float bowl that had a hairline crack.
Switch bowls on carbs to rule that out.

[75 super sport]

Well i checked the over flow tubes, and they are not cracked but seem to be plugged up so i am going to buy new tubes tomorrow. The overflow tubes would not make my carb leak like that tho would it? I mean, if it wasnt plugged it would come out of the tube instead of the fittings, but why is it overflowing? Might i mind you that these are freshly rebuilt carbs, sand beaded and all, and the floats are set to factory( i have not checked this personally). Should I pull the carbs off and check the floats myself or any other idea? Thanks in advance guys.

[bollingball]

Well somebody has to check them. Who cleaned them and put them back together? If not you then see if they will back up there work. Unless it was a freebie from a friend I would take it back.When you say tubes do you mean the rubber tubes ? what about the stand pipe inside? No they are not the cause floats are not sealing.

Ken

[75 super sport]

No, I sent them out for a rebuild from a guy who specifies in sohc750 carbs. So I had pretty good faith in not checking the float height before i installed them.

*OK so i noticed that my overflow tube was clogged. I took it off and started the bike, it did not leak at first then it started overflowing. Shut it off, tapped on the float bowl and it didnt leak again for the time that i ran it. I am going to take the carb off tomorrow and check the float levels. Maybe its jetted too rich? 110 mains, 4-1 exhaust, pod filters. Any help is appreciated thanks guys.