Topic: Leaky carb but NOT from overflow tube

[miketayc]

Hey everyone,

I'm trying to locate the source of a gas leak from the carbs on my honda cb550. The tricky part is that is definitely not coming from the overflow tubes. It only occurs on the leftmost carb, and not while riding. It's a pretty slow leak and only occurs after the bike has been sitting for a while, like overnight. I was thinking the carb bowl might be loose or the gasket worn(but these are only a couple months old). But I don't think this can be the case because there is visible layer of gas above the float bowl too. pretty much half the carb will have this layer of gas above it I've attached an annotated picture for reference.

[miketayc]

I was wondering if someone has seen such an issue before, or had any suggestions on how I might locate the source of the leak.

[evinrude7]

maybe clean it then powder it up with talc and come back a few hours later?

[kerryb]

Have you ruled out a leaky gas tank or petcock?

[eigenvector]

Would you mind restating your last sentence?  I'm afraid I got really confused by what you were describing.  "visible layer of gas above it"

[Stev-o]

I would check the float height and the gasket.

[Mr. Mike]

Maybe park it, fuel valve off of course, drain the #4 bowl and check it in the morning. Touch the bottom of the bowl drain screw in the AM to see that it is also dry. If wet still, get your LED flashlight and a mirror to peer at the undersides.

[Airborne 82nd]

Maybe park it, fuel valve off of course, drain the #4 bowl and check it in the morning. Touch the bottom of the bowl drain screw in the AM to see that it is also dry. If wet still, get your LED flashlight and a mirror to peer at the undersides.

Do you mean #1

Hey everyone,

I'm trying to locate the source of a gas leak from the carbs on my honda cb550. The tricky part is that is definitely not coming from the overflow tubes. It only occurs on the leftmost carb, and not while riding. It's a pretty slow leak and only occurs after the bike has been sitting for a while, like overnight. I was thinking the carb bowl might be loose or the gasket worn(but these are only a couple months old). But I don't think this can be the case because there is visible layer of gas above the float bowl too. pretty much half the carb will have this layer of gas above it I've attached an annotated picture for reference.

[greenjeans]

Do you park your bike on the kick stand or engine stand?   If you leave it on the kick stand, some of the gas left in the carbs will run down to the left carb since it is the lowest point.  The bowl will then fill to a point that is just over the seal.  If the seals aren't great, you will get a little seep if it sits.

I'd also do a "clear tube" method to double check the actual level of gas in the bowl.  It's possible that that particular bowl fills a bit higher than the rest as well.

You could also just run the gas out, or drain it from the fuel bowls if you are going to park it for an extended time.  Ethanol sucks if you leave it sit for long periods.

* the photo posted is the right carb (as you sit on the bike)  Is that the one that leaks or is it the other side ?   If that is the one, disregard what I said earlier and double check the actual fuel levels with the "clear tube" method, and/or get new gaskets.

[Mr. Mike]

“Leftmost” -I suppose so, I just focused on the pic...rightmost.
But either way....

[jc914]

I had a similar issue, it turned out the "O" rings in the "T" fitting between two carbs were old and needed replacing.