Fuel leak from #4 carb

[pit-fighter]

OK guys i let my old lady ride my bike and she laid it down on the right side now i have a gas leak ...the leak is coming out of the #4 card when the bike is turned off and sits for a while it comes out of the card where the butterfly is.. and leaks out of the air snorkle tube down onto the engine...i looked for phisical damage but didn't see anything wrong...And it dosen't make any difference where i set the petcock..offf.on...res..prime....it still leaks....any idea's what could be wrong?..please help!!!

[Pat Kelly]

A stuck float will allow fuel to leak out the carb. Old-school attemt (that has worked for me occasionally) is rap #4 float bowl with the handle of a screwdriver. Sometimes that will free-up a stuck float. Otherwise remove the carbs and take-off the bowl and see what's going on

[pit-fighter]

Tried the screw driver trick but didn't work still leaking...but thanks for trying to help pat...

[TopCatGr58]

Such a thing as a bad LAY!

Hey there Pit,

After a strong dumping, you could have stirred up some rust particles in the tank, and then they could have flowed down into the carbs, causing the float needle to not make a good seal. But, it's probably the float itself, may have gotten slightly wedged on the pin, or against the side of the bowl preventing it from actuating properly!?

Along this same line, since you described 4 petcock positions, you probably have a SPECIAL, and IF you still have the Octopus, that same crud could have contaminated the Octy valve not allowing it to seal properly, cause it shouldn't flow in the OFF position!! Need to pull the hoses from the petcock to verify that OFF works, might need to rebuild it as well, but #4 shouldn't leak, so something's wrong with it at least!

I doubt that the float needle valve fell out of the seat while the bike was on it's side, but might have gotten wedged diagonally between the float and the seat???

Best to pull the carbs and the bowl and investigate! Good luck!
Let us know what you find!
T.C.

[pit-fighter]

HI topcat

Im gonna take the line lose to make sure the petcock is working in the off position...thanks for the idea...just hate to pull the carbs but looks like i might have to...never done that before..geuss its best to try all the simple things first..but thanks for all the help and idea's you guys can give me..i bought a set of carbs off ebay..just incase they needed to be replaced.

[scalded dog]

If you have a clymer manual, the removal of the carbs, is spelled out well. If not, remove gas tank, remove left and right side covers, use a screwdriver to take the intake clamps and the air intake clamps loose, take the side bolt on each side out of the chrome air breater, where it attaches to the frame, take the top bolt off whre it attaches to the frame, slide the intire air brather back, take loose all tubes hooked to the carbs, pull back on the carbs, slide them out of the left side of the bike, half way out take the throttle cable loose. re-install the same way. Later 'Dog

[pit-fighter]

I ordered a clymer manual from ebay last night....I turned both petcocks to the off position and still have gas leaking from the #4 card...Does that mean both petcocks are bad?...would that be the problem?...strange thing is that the carb never leaked until the bike was laid on its side....

The weather is gonna be bad the next few days so im not gonna be able to work on the bike much...but when the weather gets better i hope you guys can help me figure it out.

[TopCatGr58]

I hate to ask this, please don't think anything condescending about it, but are you sure you are turning the petcocks to off? The function is where the Large part of the handle is pointing or covering!

The Petcocks might have gotten damaged from the drop, the rubber valve may have been brittle, and this fall caused it to break up, so that it's not valving properly no matter what position you put the handle in?

IF your special is hosed according to OEM, then only the Right petcock provides fuel for the #4 carb, but no telling what the PO may have done, such as linking the supply lines between the left and right petcocks!?
T.C.

[pit-fighter]

No problem topcat..im glad you cleared that up for me..i wasn't sure about it to start with.....I did a little more testing...if i turn both petcocks to the off position the leak stops...if i turn the petcock next to the #4 card off and leave the other one on then i get the gas leak...looks like both petcocks need to be in the off postion to stop the gas leak.

[TopCatGr58]

Gettin' Hosed!

Hey Pit,

This still doesn't sound right? The fuel should NOT flow from the left petcock into the right bank of carbs and vice versa. Take a look at this hosing diagram, and compare how yours is setup? You never said whether you still have the Octopus or not!?

T.C.

[fxrer]

Hey Pit,

The operation of the petcocks and diaphragm (“octopus”) is different between a Special and Standard. On a Special, the four positions are ON (lever pointing down), PRIme (lever pointing back) REServe (Lever up), and OFF (lever forward) In PRI, fuel flows directly to the carburetor. In ON or RES, fuel flows first to the octopus. When the engine is running, vacuum opens the diaphragm in the octopus, and allows fuel to flow to the carbs.

Since it ran OK before, but leaks after, and it only leaks from carb #4 (not #3), my hunch is a problem with the float needle in carb #4; it may have come out of the seat somehow, and will not seat properly.

Fortunately, on the outboard carbs #1 and #4, you can remove the float bowls without removing the bank of carbs. You will need a right angle #2 Phillips screw driver. Or, what I use is a #2 bit about 2” long, and a ¼"drive ratchet with ¼” hex socket. You can access and loosen the 4 screws that attach the float bowl. Drop the bowl, and you’ll see the float. Check to see that the float pivots on the pin properly. Maybe the float needle is cockeyed, and all you need to do is reach in with a small screwdriver and re-orient it into the seat.

If not, you can remove the float, but be VERY careful removing the pin, or you can break a post. Read ALL the threads here about how to do this, including using the new tool fabricated by Ken Talbot just for this purpose (see recent thread started in Dec by CUBuffs for a picture).

Personally, I use the side cutter technique and haven’t had problems. But Ken’s tool is really slick and should be more fool proof.

[pit-fighter]

My bike is a special and it does have the Octopus on it...the weather is a little better here today..im gonna try to compare mine to that diagram.

[pit-fighter]

Finally got around to taking the float bowl off the #4 carb...looks like it might be the float needle valve...when i push the float up with my hand gas still leaks down around the needle valve...from around what looks like a o-ring...shouldn't the gas flow stop when i raise the float to close the needle valve ?...can the needle valve be tightened with a wrench?...maybe that would stop the leak...sorry if i sound stupid on this stuff ..but this is the first one i've taken apart...also with the petcock that goes to the #4 carb in the off position...im still getting a stream of gas down through the needle valve..so i geuss i have 2 problems....any sugestions on what i need to do to fix it?

[John]

From what I can see, you have a 79 SF. Brass floats gave it away. The seat assembly threads into the carb body. You could try to tighten it up a little. There should be a fiber gasket under the hex of the seat assembly, not an O ring. As far as fuel leaking past even when the petcock is off could mean that the other petcock is open and fuel is flowing past the diaphram in the octopus. Check to see if it is off. It has been said here that you can take some polishing compond on a Q tip and go down inside the seat to clean it up, so the needle will seal it off. I haven't tried it, so I don't know if it works or not. Have you checked to see if the float has sprung a leak, and fuel has seeped into it? That will cause a no sealing problem.

[pit-fighter]

Dont think the float has a hole in it and both petcocks are in the off position....Does it take a special tool to tighten the valve...or do i have to remove the float and use a socket and ratchet?