Fuel leak after cleaning carbs

[Erich Z]

Well, good news is after I put it all back together, the bike started and ran, albeit not all that well.

Bad news is there seems to be quite a fuel leak from the carbs somewhere, there was a puddle right below them after running for 2-3 mins. Time to disassemble again i suppose, sigh.

I stripped one of the float bowl screws too when reassembling, so that could be where it's leaking from? I reused the old float bowl gaskets too, because the ones I ordered from Z1 turned out to be the wrong shape/size.

And here I was hoping to be riding on a nicely tuned bike by the end of the week. UGH!

[doctorgonzo]

Probably the stripped screw, or a stuck float or something. You can run pretty damn ratty float bowl gaskets (I think mine might be original and have several tears in them) without leaking.

[NICK!]

Not unusual for freshly cleaned carbs to leak or weep a bit at first. Try the old tapping on the carbs trick with a soft hammer or soft block of wood to see if theres a stuck float.

You want to tap "firmly" but not so hard as to break the carbs.

Of course this only works if it is a stuck float or a piece of dirt on a needle. Best thing to do first is find out where the leak is coming from.

[Erich Z]

You want to tap "firmly" but not so hard as to break the carbs.

Good advice if I've ever heard it!

[Griffin]

Most carb leaks come from the fuel line o-rings in between the carbs. The other main source of leaks is a stuck float will allow the bowl to overfill and then leak gas through the airbox or vent line.

It doesn't take much to seal the bowls to the carb body. I've still got the original gaskets on all my bikes, and none of them leak.

[bwringer]

Agreed. Another piece of GS lore to have engraved somewhere safe:

"If fuel is dripping from your carbs, IT AIN'T THE %$#@&! FLOAT BOWL GASKETS!!!!"

[spchips]

Agreed. Another piece of GS lore to have engraved somewhere safe:

"If fuel is dripping from your carbs, IT AIN'T THE %$#@&! FLOAT BOWL GASKETS!!!!"

Sometimes it is. As mentioned above, you can get away with pretty nasty ones, but not always. Sometimes, they are just too old and too hard not to leak. I put gas+oil seal-all on a torn corner once to keep it from leaking.

[mighty13d]

make sure you replaced all of the o-rings because the one that you miss will be the one that will leak. throw a new o-ring on the drain plug that you messed up the threads on, that will help it seal if you didn't.

[Erich Z]

Oh I didn't mess up the threads on the drain plug, I messed them up on one of the float chamber attachment points. It doesn't look to be leaking from there, possibly from where the fuel line goes into the carbs.

Any easy way to leak test the carbs off the bike? Thanks folks.

[80GS750]

i dont even pull the drain plugs unless i have to...

i would rather pull the carbs and take the bowl off... what are you really gonna do other than drain the gas with that screw??? doesnt help troubleshooting at all, IMO

my float bowl gaskets are original i think too, they are old and nasty, but hold up just fine.

if its leaking that bad you may be able to spot it or feel it out when the bike is running.... dry it all off, start it up and spot your leak!

[Cassius086]

Most carb leaks come from the fuel line o-rings in between the carbs. The other main source of leaks is a stuck float will allow the bowl to overfill and then leak gas through the airbox or vent line.

It doesn't take much to seal the bowls to the carb body. I've still got the original gaskets on all my bikes, and none of them leak.

Bingo! Ladies and gentlemen, we have a likely winner here!! Just takes a little twist of the carb rack to make one of them leak....

[gpans]

I had a carb leaking problem and it turned out to be the float needle being stuck, but not jammed completely up. The carb kept on filling with gas and draining out the nipple in the bottom every few seconds. It would flood out gas, then stop, then flood out more gas. if that sounds at all like your problem you might want to look at your floats. Good luck!

[doctorgonzo]

Fingers crossed for me. I'm so ****ed about losing my side cover I don't even want to ride for a few days so I'm going to put in my oring set, replace diaphragm, tear the carbs totally doen for the first time.

[MTHughes]

I have the same problem with my 79 GS750. I replaced all the gaskets and o-rings, put the carbs back on and now gas always drips from the little nipple on the #4 carb. I've replaced the floats and the needle from a spare carb I have and it still does the same thing. It will start dripping within a minute of starting the bike. I'm a little lost as to what else the problem could be

[greg78gs750]

well, mine leaked a little too after my rebuild this spring. i was screwing around with needle height etc, and so taking them apart a couple times, finally my BRAND NEW gaskets seated. but they were definitely leaking around the gaskets. i think sometimes it just takes a few tries....if it is the fuel t or tubes, i wrapped mine with some teflon tape, they werent leaking before, but they are not leaking now either, and seated/sealed much tighter. if it is this, give it a try, just a couple neat wraps.