Should overflowing gas drain thru vent hose? (Picture) Please verify. Thanks.

[DreamV4]

Diagnosing leaking carb:

 

[maleko89]

If float/float valves aren't functioning correctly, yes. Check needle valves, float, float tang, bent float pivot pin, etc.

 

[02GF74]

the overflow hoses are 4 small hoses that poke out through the brakcets on the sides, see below

what you have marked are vents that fit onto the top of the airbox - i cannot see how the fuel can get that high so my answer has to be no.

 

[DreamV4]

Found bowl drain holes and bolts:

 

[02GF74]

Whilst you have the carbs on the bench, it's worth undoing the drain screws in case they are seized and to clean them, debris accumulates there.

Also check the o rings are in good condition.

If fuel flows out, that would indicate needle valves are not sealing either due to debris, wear in the tip (tips nowadays are viton which is softer than older brass), needle valve seized or float damage. I'm sure you will have dealt with this before
.

 

[one2dmax]

the overflow hoses are 4 small hoses that poke out through the brakcets on the sides, see below

what you have marked are vents that fit onto the top of the airbox - i cannot see how the fuel can get that high so my answer has to be no.

View attachment 82957

This is incorrect. Those are drain hoses which are only used when you open the drain screws. The vent is also the overflow when the float seat sticks or has debris in it that lets the carbs fill up too much.

 

[dannymax]

The title of the thread..."SHOULD" overflowing gas.......

Answer - Definitely not! Raw fuel should never 'overflow' anywhere out of the carbs.

 

[RadiumPHX]

I am curious why your left slides are in the up position.

 

[DreamV4]

I am curious why your left slides are in the up position.

I used pics of my carbs before overhaul.
Intermittent overflowing is sign of sticky float (?) after cleaning and installing them.

 

[RadiumPHX]

I used pics of my carbs before overhaul.
Intermittent overflowing is sign of sticky float (?) after cleaning and installing them.

overflow of fuel can be a compromised float, improper float adjustment (float tab), a worn/failed seal at the needle seat or debris at the needle seat. You can use a clear fuel line spliced onto the bowl drain hose, with the drain screw open to gauge the fuel height in the bowl in an attempt to identify which carb is suspect.

 

[02GF74]

This is incorrect. Those are drain hoses which are only used when you open the drain screws. The vent is also the overflow when the float seat sticks or has debris in it that lets the carbs fill up too much.

Another school day. I seem to remember fuel coming out from the drain screws, either I rememberef it wrong or undid the screws too much.

My thinking it wasn't the vents since if fuel starts to pour out of them, the fuel level had reached the point where surely thered be a drilling for the fuel to go through and end up in the cylinders.

 

[DreamV4]

Increased fuel level will go thru the lowest hole.
All jets are lower than vent, which means (it seems logical), it will flow thru idle jet and main jet.
UNLESS!!!!!!
Fuel flow is much higher than what jets can let thru, and it will go thru vents like Sean said. He is always right!!!
Summary:
1. When engine runs, it will flow thru vents (extra fuel from jet will be sucked in by engine)
2.After engine stops, fuel will go thru jets until level goes to normal.

 

[desert_max]

I had a nice ‘90 recently that the guy sold because he couldn’t get the carbs right. He had the vents looped back into each other because fuel was flooding out of all four! Turns out the float needles had the wire on top that was interfering with their ability to completely seat. Don’t know what kit they came out of, but I replaced them with K&L needles and the bike just hummed.

Almost kept that one…

 

[ProjectMax]

My 1985 🏍 also has this issue with the gas spitting out of a carburetor breather tube when trying to crank it over. I just received this bike and it has been sitting so I KNOW it's a PROJECTMAX before I can ride it. I freed-up the vacuum slides, (all four were stuck), and will try tapping on the offending carb breather tube to (hopefully) free a potentially stuck float. All carb work had to wait for me to clean rust out of the tank by removing it, (what fun!), and using vinegar soak for a day, then muriatic acid for a couple of minutes, (quickly followed by baking soda and water to neutralize). Now clean as a whistle inside and reinstalled. Also, replaced fuel pump including retrofit of the inlet/outlet end and mounting bracket since the replacement I got from eBay wasn't a perfect match. I thank God I have a garage. BIKES ARE MEANT TO BE RIDDEN - - NOT STORED!! (This is my first post - thank you for being here and sharing. So many of us are wrenching riders and can use the benefits of other's experiences.)

 

[Fire-medic]

I had a nice ‘90 recently that the guy sold because he couldn’t get the carbs right. He had the vents looped back into each other because fuel was flooding out of all four! Turns out the float needles had the wire on top that was interfering with their ability to completely seat. Don’t know what kit they came out of, but I replaced them with K&L needles and the bike just hummed.

Almost kept that one…

I also use the K&L float needles. Having had a number of bikes, it's common to have to fix botched 'overhauls' by well-intentioned but skills-lacking former owners. I just hope the guys didn't get into the engines.

 

[wayne billings]

when you find that the ham fisted hary's have been in the engine 'hold onto your patience and let go of your savings'.

 

[JMax92]

I had this exact issue last week with no2 carb overflowing and flooding the no2 cylinder. I assumed a stuck float.
Disassembled no2 carb, reassembled and problem went away, so pretty sure a bit of gunk was stuck either in the float or the needle.
After ensuring no more leaks, balanced the carbs and all is good again.

 

[ProjectMax]

My 1985 🏍 also has this issue with the gas spitting out of a carburetor breather tube when trying to crank it over. I just received this bike and it has been sitting so I KNOW it's a PROJECTMAX before I can ride it. I freed-up the vacuum slides, (all four were stuck), and will try tapping on the offending carb breather tube to (hopefully) free a potentially stuck float. All carb work had to wait for me to clean rust out of the tank by removing it, (what fun!), and using vinegar soak for a day, then muriatic acid for a couple of minutes, (quickly followed by baking soda and water to neutralize). Now clean as a whistle inside and reinstalled. Also, replaced fuel pump including retrofit of the inlet/outlet end and mounting bracket since the replacement I got from eBay wasn't a perfect match. I thank God I have a garage. BIKES ARE MEANT TO BE RIDDEN - - NOT STORED!! (This is my first post - thank you for being here and sharing. So many of us are wrenching riders and can use the benefits of other's experiences.)

Speaking of BREATHER TUBES - - does anyone recognize THIS modification? (Looks like he put gas filters at the end of short overflow tubes.) He has a video here:

Does this work fine without presenting any problems?
​

 

[desert_max]

Speaking of BREATHER TUBES - - does anyone recognize THIS modification? (Looks like he put gas filters at the end of short overflow tubes.) He has a video here:

View attachment 83749
Does this work fine without presenting any problems?
​

That'll work fine unless those happen to be plugs and/or aren't open to the atmosphere.