Carbs overflow tube spews few drops of fuel

[Kool_Biker]

Hi, I have just noticed that following a ride, even a moderate one, the carbs overflow tube of my Z, spews a few drops of what seems like fuel on the garage floor.
Is this normal?
All float bowl drain screws have new rubbers, and are tightly screwed in.
Am I missing anything?
Best, Aris

[steve murdoch icoa #5322]

Just sounds like the float levels are a bit too high.
Is the bike running rich? Any gas in the airbox?

[Jeff Bennetts]

Could be a cracked overflow tube in the bowl, happens alot in these old Hondas.

[Kool_Biker]

I think both suggestions make sense, next time my carbs are off I will double check the floats as well as for the integrity of the overflow tubes in the bowls.
I also like very much the idea of testing the fluid level in the bowls with a transparent tube, ensuring all six are correct and equal.
So much collective now how in the forum !!!
Thanks, Aris

[daves79x]

The 2 most likely causes are a cracked standpipe, as Jeff mentioned, or a weepy float valve. You need to remove the 6 rubber drain hoses and you will quickly see which one(s) leaks. Then attack that carb to see what's the matter. If you end up taking the carbs off to fix this, do yourself a favor and bench test them for at least 24 hours to see if you have leaks. With your manual fuel valve, you REALLY have to be careful to turn off your fuel any time you stop, knowing you have a leaker. You can fill up a cylinder pretty quickly with fuel if you don't.

Can't remember - did you use Honda float valves or aftermarket? This 'weeping' is very common with aftermarket valves and has been chronicled here often. Please don't take this leaking lightly, as you know, it can cause huge problems. Keep us posted.

Dave

[tevan]

kool biker,
I seen that you suggested the clear tube float level check. Where should the fluid level be on the bike and also where should it be if you have the carbs off and level on the bench? I just happen to have a set off the bike as I write. thanks

[CopperCollar]

I was having the same issue with a set I had rebuilt. Pulled them off again and the float levels were fine, overflow tubes were fine. I think, at least in my case ....when I park the bike after a ride that damn ethanol fuel boils off and condeses in the drain tubes then drips on the floor. That's my theory at the moment. This summer will really tell though as our temps can reach 110.

Mike

[Kool_Biker]

The 2 most likely causes are a cracked standpipe, as Jeff mentioned, or a weepy float valve. You need to remove the 6 rubber drain hoses and you will quickly see which one(s) leaks. Then attack that carb to see what's the matter. If you end up taking the carbs off to fix this, do yourself a favor and bench test them for at least 24 hours to see if you have leaks. With your manual fuel valve, you REALLY have to be careful to turn off your fuel any time you stop, knowing you have a leaker. You can fill up a cylinder pretty quickly with fuel if you don't.

Can't remember - did you use Honda float valves or aftermarket? This 'weeping' is very common with aftermarket valves and has been chronicled here often. Please don't take this leaking lightly, as you know, it can cause huge problems. Keep us posted.

Dave

Dave, Thanks, your advice is appreciated, luckily I am aware of the seriousness of a leaking float valve in a CBX.

HOWEVER, my 'problem' is 10 ~ 15 drops, on the floor, AFTER a run. What seems to me as a transient effect.
My float valves have been purchased from TIMS but somehow I do not think the problem lies there. I am more inclined towards one or more float levels inaccurately set, allowing (hot, expanded) fuel to escape through a standpipe?

But will get them out in time and thoroughly go through all this.

Cheers, Aris

[Kool_Biker]

kool biker,
I seen that you suggested the clear tube float level check. Where should the fluid level be on the bike and also where should it be if you have the carbs off and level on the bench? I just happen to have a set off the bike as I write. thanks

Please check thread "MISFIRE & HESITATION" in CARBS. It's all there.
Cheers, Aris

[Kool_Biker]

I was having the same issue with a set I had rebuilt. Pulled them off again and the float levels were fine, overflow tubes were fine. I think, at least in my case ....when I park the bike after a ride that damn ethanol fuel boils off and condeses in the drain tubes then drips on the floor. That's my theory at the moment. This summer will really tell though as our temps can reach 110.

Mike

Mike I like your theory, to be proven in the next few weeks as temps in Greece soar, makes a lot of sense.
Cheers, Aris

[ajs350]

kool biker,
I seen that you suggested the clear tube float level check. Where should the fluid level be on the bike and also where should it be if you have the carbs off and level on the bench? I just happen to have a set off the bike as I write. thanks

tevan
I measured float height with the carbs on the bench supported by 2 pieces of 4X2. Put one under the carb support bracket and the other under the 2 middle carbs bowls. This I found was the same angle that they were on the bike.
Here's a picture of mine set this way (double click on it to make it larger). Note the fuel level shown here is too low. It should be level with the top of the support bracket screw.
Ross

Correct level.

[tevan]

So what is the float level if the carb. body float bowl seam is level? I am trying to get away from the unlevel part of this because it you aren't with the perfect angle as the bike it will be different. thanks

[ajs350]

tevan
I had my carbs off again this week so took this picture which shows the fuel level of 1 and 3 with the carbs on the bench. Ross

[Goss]

In situ fuel level.

Goss MM Fuel Level.jpg

Regards

Goss