Topic: Replaced Carbs, hoses go ??

[mongeon]

Regarding a '74 cb550.  I just put my carbs back on.  There are two hoses next to the throttle spring, between carbs 2 and 3.  They are NOT the lines to the fuel tank.  Do they connect to anything?  I took them off a while ago, and could not get back to it until now.

Thanks
Chris

[Bob Wessner]

Could they be the vent lines to maintain atmospheric pressure within the fuel delivery system (carbs, bowls, etc.).

[mongeon]

I think that's what they are, but I am not sure.  There are four, one at the bottom of each carb bowl, that are not attached.  I think these two may also be unattached, but I want to make sure.

[Warlock]

Greets,
The 2 hoses that are located at the rear between the #2 and #3 carbs are bowl vents. The 4 hoses from the bottoms of the bowls are the fuel overflow hoses. All these hoses should be routed behind the back of the engine and down between the swingarm and the frame along with the crankcase breather tube.

Ride On....

[scadaman29325]

Greets,
The 2 hoses that are located at the rear between the #2 and #3 carbs are bowl vents. The 4 hoses from the bottoms of the bowls are the fuel overflow hoses. All these hoses should be routed behind the back of the engine and down between the swingarm and the frame along with the crankcase breather tube.

Ride On....

That explains the 'extra' hoses that I have. But some yahoo disconnected those and put a 'U' shaped hose 'between' and connecting the two bowl vents to each other. Was this guy an idiot or a pro?

BTW, sometimes my carbs overflow like sombody poked a hole in the gas tank. Could that be causing the overflow? I've tried cleaning but no luck (yet).

Later, Phil

[newcbguy]

thanks I was about the ask the same question!

[rlarkin70]

anyone know a good source for those vent/overflow hoses? is that a generic item that a motorcycle dealer should carry by the spool? mine are pretty ratty looking with some cracks in them, so I want to replace them.

[newcbguy]

for the overflow hoses you should be fine with vacuum hose since there shouldn't be gas under pressure in them. you can also get fancy and get some clear line from home depot if you like but it will soon yellow if gas  passes through.

[TwoTired]

Warlock hit the nail directly on the head.  Carb bowl vents.

The bottom tubes are overflow tubes that will act as bowl vents (unless they are over flowing or plugged with insect nests.)

That explains the 'extra' hoses that I have. But some yahoo disconnected those and put a 'U' shaped hose 'between' and connecting the two bowl vents to each other. Was this guy an idiot or a pro?

I'd go with the idiot assessment.  Or, "The lord looks after fools and little children".

BTW, sometimes my carbs overflow like somebody poked a hole in the gas tank. Could that be causing the overflow? I've tried cleaning but no luck (yet).

Sound like a float/ float valve issue.  Float setting wrong, float pivot binding, or something foreign blocking the valve from closing.  Learn to turn off your petcock while parked.

The vent hoses can be purchased at a Honda dealer in bulk.  3.5 mm   (Be sure to bring cheese to go along with the whine regarding cost.) 

Vacuum hose will still dissolve from the fuel vapor, making it a poor choice for this mission.

Cheers,

[scadaman29325]

Warlock hit the nail directly on the head.  Carb bowl vents.

The bottom tubes are overflow tubes that will act as bowl vents (unless they are over flowing or plugged with insect nests.)

That explains the 'extra' hoses that I have. But some yahoo disconnected those and put a 'U' shaped hose 'between' and connecting the two bowl vents to each other. Was this guy an idiot or a pro?

I'd go with the idiot assessment.  Or, "The lord looks after fools and little children".

BTW, sometimes my carbs overflow like somebody poked a hole in the gas tank. Could that be causing the overflow? I've tried cleaning but no luck (yet).

Sound like a float/ float valve issue.  Float setting wrong, float pivot binding, or something foreign blocking the valve from closing.  Learn to turn off your petcock while parked.

The vent hoses can be purchased at a Honda dealer in bulk.  3.5 mm   (Be sure to bring cheese to go along with the whine regarding cost.) 

Vacuum hose will still dissolve from the fuel vapor, making it a poor choice for this mission.

Cheers,

Yeah, I was thinking 'idiot' too, but sometimes I can be accused of that.

Yeap, I need to do some cleaning/adjusting on the carbs.

As for turning off the petcock... (Hold on a sec...I had to go check, again)... Guilty.
I mostly ride a '78 GL1000 that has NEVER had the petcock closed. The guy said he never messed with it and he didn't want to rebuild it if it messed up, so I haven't messed with it either. No problems on the GL (but it has a fuel pump).

Oh yeah, the cheese... don't you love a smarta$$, especially a funny one.
I need lots of cheese for all the whining I've been doing.
What goes with cussing? I did a LOT of that getting those carbs back on. I thought I was going to have to pull the engine, or at least drop the front motor mounts...
Took me 2 hours to get the airbox and carbs back on, I'm still not over that.

Thanks for the help.
Later, Phil

[Somemonkey]

I'm actually having the same problem with my carbs leaking gas through the overflow valves. I adjusted the floats to 22mm as the book suggests but they're still leaking. The floats are in good shape and don't have any holes in them. Do you think it's because of faulty needle valves?

[TwoTired]

I'm actually having the same problem with my carbs leaking gas through the overflow valves. I adjusted the floats to 22mm as the book suggests but they're still leaking. The floats are in good shape and don't have any holes in them. Do you think it's because of faulty needle valves?

Sound like a float/ float valve issue.  Float setting wrong, float pivot binding, or something foreign blocking the valve from closing.  Learn to turn off your petcock while parked.

Additionally, the needles and seats become "married" over time for a good sealing fit.  Swapping needles and seats among the carbs can make them leaky.  Finally, they can become worn, both needle and seat, to require replacement.  Often when this occurs, you can feel a ridge with your fingernail on the cone of the needle.

Cheers,

[TwoTired]

What goes with cussing?

Toast and Jam.  Though not necessarily in that order...

I did a LOT of that getting those carbs back on. I thought I was going to have to pull the engine, or at least drop the front motor mounts...
Took me 2 hours to get the airbox and carbs back on, I'm still not over that.

Yes, improper install procedure can be frustrating.  If you do this again, here's the easiest way I know:
Remove the band clamps **completely** from the rear rubber couplers.
Remove the two bolts that anchor the filter box.  (This allows the couplers to move back the quarter inch you be happy to have.)
Install the front rubber couplers first.
Spray silicone or soap spray onto the rear rubber couplers.  And, similarly lube the inside and "faces" of the front rubber couplers.
March the carbs across the bike from left to right, using a dull tipped probe to push the rear couplers out of the way.
You will have less wrestling to seat the carbs into the front couplers if they aren't 30 years old and set in their ways.

(The next time I do this, I'm going to try laying a flat sheet of metal (like a steel rule) across the rear couplers to act as a ramp that helps deflect the rubber bits. I can see it helping in my mind.   But, I haven't tried this yet.  I imagine the age hardness of the rear couplers may impact the plan, as they may retreat into the plenum box instead of the collapsing in compliance.    ) 

Cheers,