Topic: HELP 2 CARBS LEAKING? NOT FROM THE GASKETS! LIKE A OVERFLOW OR SOMETHING..HELP

[MATTS WING THING]

I HOPE SOMEONE CAN HELP ME...I AM HELPING MY FREIND GET HIS 80 750C UP AND ATTOM...IT WAS LAYING ON ITS SIDE FOR 6 YEARS(MOTOR WAS FROZEN AND A RATS NEST IN THE AIRBOX)AND ALL THE LITTLE THINGS THAT GO ALONG WITH IT! GOT THE BABY RUNNIN 20 HOURS OF TINKERING(PULLING APART AND PUTTING BACK TOGETHER). NOW SHE RUNS BUT AFTER ABOUT 10-15 MINUTES OF RUNNING THE 2 INNER CARBS WILL START TO PISS GAS OUT OF THE BOTTOM. LOOKS LIKE AN OVERFLOW ! IF ANYONE HAS ANY IDEAS PLEASE LET ME KNOW AS SHE IS ALMOST READY FOR THE ROAD!(LEGALY HE HE HE)
I REALY APPRECIATE ALL THE HELP IN ADVANCE

[DrMark]

Sounds like the floats are sticking and allowing the fuel to exit out the overflows.

[fang]

ditto that about the carb's float needles.  Sometimes the needles will have some goop in them and this will prevent them from closing all the way.  A common culprit is rust in the gas tank....  Get a good inline filter (or two if it is bad), and clean out the carbs again.  This should help.

If this does not fix it then you probably will want to just replace the float needles and seats.  These are relatively cheap and easy to do.  In fact, it might be a good idea to replace them just for kicks/preventive maintenance

Peace and grease
-fangA.

[sadams1954]

I had a problem with fuel leaking out one of the overflow tubes on my CB400A, cleaned the carbs, replaced the float needle valves, set the float height...no dice, still leaked fuel. Out of desperation, I pulled the float bowl and filled it with fuel and gas ran out the overflow tube. While holding my finger over the top of the overflow tube blew air into the rubber hose....I had lots of bubbles! I dumped out the gas and checked closly and found a hairline crack in the overflow tube from the top all the way to the bottom of the floatbowl. I filled the crack with solder and it has been troublefree since.  Hope this helps.

Steve

[KB02]

That actually happens allot. I had a buddy with a cb400 (twin). Both his carbs were doing that. The tube is made from a sheet that is bent into a tube. sometimes the seal just lets go.

[74cb750]

Mine just started doing that on carb #3
After I cleaned them.
Will check for hairline cracks. Probably did something when I cleaned them with
the Dremel tools.
peace,
michel