Gas leaking main air jet?

[egsols]

I finally found the gas leak but don't understand why its leaking.

The manual calls this port the main air jet (pressed in) and I think the passage runs to the main jet under the main needle. I can't figure out why the gas is coming back out this port, on the number one carb.

Just replaced all float needles and seats and checked all float
levels.

Now what??????

[mro]

Where your arrow is pointing is above the float bowl.
When engine is off for fuel to reach there it has to get past the float needle.

Float hanging up or something between needle and seat.
How is the o-ring under seat?, can leak there too.


mro

[egsols]

mro,

no oring, 79 carbs. Brand new float needle and seat, can't see where float could be hanging.

Had same problem before I replaced valves and seats.

Doesn't leak at idle. Because the manaula called the mair air jet I figured I would rev it up a few times past 3000 rpm. It started to leak after that and kept leaking after I shut it off. Could I be having a problem with my main needle, the one going into the emulsion tube?

This has got me stumped.

[AlanB]

Hi Egsols,

MRO is right; fuel CANNOT get to there without passing through (or round?) the float needle and seat.

Your problem is still with them.

Do the floats "float".... or sink?

best of luck.

AlanB

[mro]

kept leaking

So your seat be screwed....,
still has to get past float needle.

On a G, I was playing with different float heights. Ran grate stock height but wanted to know effect of higher fuel levels at different rpm. Once set it 2 mm lower (float set with micrometer) float would hang up sometimes and fuel came out carb even with engine running. Tapped on float bowl with the handle of a large screw dirver and it stopped once. Re-set to stock height and stopped playing.


mro

[egsols]

Tested floats in hot water, all floated, no air bubbles.

Replaced drain plugs with drilled out grease nipples. Checked fuel level in clear tubes attached to grease nipples, all exactly the same.

Question....if float is sticking open wouldn't the fuel come up through the emulsion tube first?

[egsols]

Just another thought....it almost seems as if there is a vaccuum at play, sucking or pushing the fuel out somehow.

I did test the two carb vent tees and they are clear and working fine.

[red bandit]

When float needles leak just a little, sometimes gas comes out the main air jet. Sometimes even new float needles leak. Take out needle and seat, hold needle tip with pliers, careful not to damage it. Spin seat with other hand, kind of like lapping them together. I've had good luck with this even with old ones. Make sure you don't have crap in the gas line/tank first.

[boyat68]

egsols:

It really is the floats or needles sticking, you can prove this to your self by threading a piece of dental floss/string around the float and pulling the two ends down the drain plug hole. Bolting the bowl on and the carbs upside down, gently pull on the two ends and see at what point things stick. I did this with my carbs and found that the floats/needles stick often when the carbs are dry. I bent the floats and post tang untill things seem to not stick with the string method. It took about 100 tries (maybe) before I was satisfied. I then ran the fuel level test about fifteen times and bolted the carbs back on the bike and synched and adjusted and rode the bike around the block. No leaking. I checked the synch and air pilot along with the idle and ran the bike every day. I let the bike set for five or six days without starting. I started the bike and she let loose. I suppose that some crud from my tank got into the needles as I see a fine rust oxide that gets pass the tower filters in the new petcocks and collects in the see through fuel lines as well as gets pass my in-line filters and collects as a fine film in my float bowls. I do not believe that the fine oxide is enough to cause the sticking, but it probably is the floats (new as well) expanding and contracting over time. I think that I have just not got them at the right spot where they dont grab something. My hat is off to those fellows that can clean carbs and get it right on the first go. Must be magic touch.

[79XS11F]

Are you using in line fuel filters. New needles and seats are useless is crap is jamming the needles up. Also check all the air vents including the pipes in the box that the vent hoses attach to. Blockages will lead to overflow of fuel.
Rob

[egsols]

Pulled carbs off, pulled off bowls, gently blew into flew line, got gas to bubble past valve on No.1.

Swapped valve from No. 1 to No.2 and No.2 to No. 1, blew again, No. 2 now bubbling. Guess new valve is not sealing.

Replaced No. 1 valve with old valve, blew again no leaks past 1 or 2.

Hooked up fuel to both lines and left for 20 minutes or so, no leaks from 1 2 3 or 4.

Put carbs back on bike, synced, adjusted pilots, resynced, shut off.

Now no. 4 carb dumping fuel. Arrrrrrrrrgh!!!!!! (not an actual quote, don't want to post my actual words)

Pulled carbs, replaced valves and floats in No.s 3 and 4 with valves and floats from my '80 set of carbs, figuring maybe the 80 float needles would seal better. Put carbs back on bike and ran clear line from the bowls so I could compare fuel height of the plastic floats.

Turned on fuel and watched it rise in No. 3 to just below the top of bowl....good, watched the fuel rise on No. 4 to just below the top of the bowl...good...no wait....it keeps going....arrrrrrgh.

I am running inline filters and I have not noticed any crud, sediment or anything other then clean fuel in the bowls. All of the vents and passages are clear. The floats do not seem to be binding on anything. The only thing I notice is that when the seats and valves are dry and I blow into the gas lines they hold. Once I get a bit of fuel past them and blow again they leak ever so slightly and then stop????

Maybe I'll try redbandit's suggestion, I'm not sure what else to do, the bike runs great (maybe a little rich) I just can't seem to keep the carbs from dumping fuel.

MRO..."2mm lower" do you mean 27.7mm versus 25.7mm stock or 23.7mm vs. 25.7mm?

Maybe mine are just a tad high? They are set to 25.7mm and the clear fuel line shows the level just below the top of the bowl.

[boyat68]

egsols:

To lower the fuel in the bowl, you raise the height of the float, this cuts off the fuel sooner.

I am going to replace my valve needles and seats with yet another new set from Z1, to see if that makes a difference.

[John]

egsols

Did you check the 'float drop? If the float drops open too far, the needle can get cocked in the seat and will not close until the engine vibration works it loose from the cocked position. Take the bowl off, and hold the carbs upright. Now look at the float needle. Do you see where it contacts the float? Do you see the tab on the float that contacts the float post? That tab can be adjusted to limit the float drop, therefore eliminating a stuck float needle. Another item to look at is the bowl gasket. It may be contacting the side of the float, causing it to hang up.

[mro]

Just a thought
If the plane of the tang were bent some sideways so as to not rest perpendicular on the float needle might be "cocking" the needle enough to allow it to leak?

Hope you know what I mean and not what I said


mro

[boyat68]

mro:

Good thought, I know exactly what you are saying. Since the valve needles are rounded on the bottom where they meet the plane of the tang, then that should not affect the throw of the valve needles as they are surrounded by the barrel of the seat. It is a good thing to check though. I still think that my problem is more likely the floats as I have plastic ones as oppose to egsols's having brass maybe. I got new floats and had to bend them every which away as they are very close to the sides and bottom out easily on the forward lip. I have bent the post tang (drop height) almost parallel so as they only drop a couple of millimeters, but enough to fill the bowls as using the sight gauge method shows. I bought the original kits from mikes, and perhaps the viton tips are hardened from sitting on the shelf or I just got a bad batch. I had ordered kits from Z1 after the first episode of leaking but had decided at first to try to get the Mikes working. and almost did, so I will try the Z1s to see if that will do. I suppose that egsols has also tried the above. Carb cleaning is not for the weak willed.