Topic: What are these tubes and why is gas pouring out? (NOT bowl overflow...)

[RainyRider]

Hi all - noobitty-noob-noob here again.

BIKE: 1976 CB550K

I just removed, rebuilt, cleaned my carbs. Bike used to run rough (see my post about tune-up stuff and clank-clank-clank noise). After plugs, cam chain adjust, valve adjust, points replace and adjust, timing adjust, oil/filter change I decided to rebuild and clean the carbs. Ordered some rebuild kits, rebuilt and cleaned the carbs.

FIRST TURNOVER: closed the choke - turned on fuel - turned key - turned on kill switch - crank engine. Started rough with a little throttle coaxing. Started up but immediately needed to take the choke off or it would die. after a minute of slightly rough idle settling out I noticed a puddle of gas, didn't see where from. Immediately turned everything off.

Next attempt: DID NOT USE THE CHOKE. tried the starter but battery was dying trying to start. Began kicking it over, wide open throttle (I'm a noob). Noticed as I was kicking that gas started pouring out again - looked and saw it coming out of the tubes (I have 6, only coming from 1 or 2 of them). closed the throttle (let go of the grip) and kicked it a bunch more, eventually started and ran great, apart from all the other things I need to fix.

Today, I started it without the choke (OK, I turned the choke on about 1/2 way) and it fired up. No problems, no gas pourage.

I believe that the gas was coming from the 2 drain/breather tubes that connect to the middle two carbs. My assumption is that I was severely flooding the carbs with both the closed choke and/or wide open throttle while starting. I am also assuming that these tubes are designed to drain gas from the carbs when it is flooded. Are my assumptions correct, or did I just make an ASS out of U and ME?

If the choke/WOT is flooding the carbs this severely, what can I do about it? I "bench synched" using the drill bit method, then backed off the idle adjust after I got it running to get it down from 3500 to about 1500rpm.

Another thing: the PO (get ready, you know what's coming...) somehow eliminated the stock air filter box/element system, bolted on something non-stock (an air filter, not a rag or anything) to the 1:4 plastic airbox, then there is what looks like chopped up 1962 Chevy radiator hose used as the 4 air intake rubbers. They seat nicely inside the plastic airbox holes and are clamped to the carb intake, little if any air is sneaking in there but I was thinking of using duct tape until I get real parts. Don't worry, I'm getting stock parts soon. I attribute some of the inconsistent idling/surging (which it does very little of) to this air system modification.

Thanks,
RR
 

[MJL]

If the carbs are flooded, you won't see any gas coming out f any tubes. If the carb bowls are overfilled, you may, depending on the carbs.  If the bowls are overfilled, you may have put the floats on upside down. It has happened before.  If the floats are in correctly, check float height. 

Bench sync is only good for the bench, now that you have it running get a real sync setup and do it right. It'll fix your inconsistent idle.

[Triffecpa]

the floats were probably stuck.  Sometimes the gas will come out of the float vents instead of the overflow tubes.

Running the motor with the gas shut off will force (unless they are stuck) the floats to drop and then when you turn the gas back on again, they will work fine.

I doubt that your inconsistent idle is do to the air box modifications.  Unless there is a blockage in one of the carb throats.

TR

[RainyRider]

So, I guess that is part of my question. What are those two tubes for? I know about the bowl overflow tubes, but what are the other two intended to do?

Thanks
RR

[RainyRider]

So, I guess that is part of my question. What are those two tubes for? I know about the bowl overflow tubes, but what are the other two intended to do?

Thanks
RR

Are they the "float vents"? And what do they do?

[Triffecpa]

In order for gas to flow into the bowls and back out again, the bowls need to be vented, otherwise you'd create a vaccum.  Normally if your floats are adjusted and working correctly, the level of gas in the carbs will never get high enough for it to flow out of those vents.  Also, the overflow tubes are designed to dump the extra gas out first (thru the brass tube in the bottom of the bowl)  However, if those are plugged, the gas will go higher in the carbs until they reach the level of the vents.

It doesn't happen often, but it can happen.

TR