unusual carb leakage: '76 cb550 four

Posted by dyelawn on Jun 26, 2014; 7:31pm
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/unusual-carb-leakage-76-cb550-four-tp4052197.html

Happy to report my '82 CB750 is running strong.  However, I'm working on restoring a 1976 CB550 (K?) four cylinder with my girlfriend, and we're having carb issues.  The bike ran great for about 1 month but now out of nowhere the #2 carb is leaking gas out of the overflow tube.  We ripped the carbs off and opened the float bowl but everything seems to pass inspection.  The floats move freely and the needle seems to press the valve closed easily when moved to the up position.  I even took the #1 bowl off and compared: the two float mechanisms seem identical.  What's more, when I put everything back together and ran gas into the carbs (still out of the bike), it seems like the #3 and #4 are leaking through the overflow tubes as well, now.

What I'm really wondering from you wise old-timers is if there is something else I'm missing, possibly some sort of spring or screw that governs gas flow and shutoff into float bowls for all the carbs at once.  What are the chances that three floats failed simultaneously after working perfectly?  This seems too unlikely to me.  What would you guys check next if you had carbs leaking but the floats/needles/pins/valves seemed fine and free of debris?  What could have caused a bunch of them to fail all at once?  Maybe I was just holding them slanted when I tested them yesterday, and that's why #3 and #4 are started overflowing?

All we did was take the tank off to switch out throttle cables.  Then this started happening.  Obviously I thought it could be the new cables causing the problem, but even with them totally unhooked my carbs are still leaking.  HELP!  These are the older style, thinner/taller carbs on the SOHC Hondas.  Thanks all.

-Dylan