Author Topic: Carb leaking, intermittently, sometimes... (Read 2564 times)

ncstatecamp · « **on:** October 29, 2013, 12:15:15 PM »

My number 4 carb occasionally leaks, but not a continuous leak. If leave the bike over night (side stand) without turning the fuel supply off I'll get a pool of fuel on the engine, some on the ground. The float height is correctly set, and brand new float stops. This only happens on number 4. I've taken the float stop out and cleaned it (there was nothing on it). Anybody know what's going on?

taggat · « **Reply #1 on:** October 29, 2013, 12:16:20 PM »

float needle seat or the seat itself?

flybox1 · « **Reply #2 on:** October 29, 2013, 12:24:47 PM »

rubber-tipped float needle? if brass, you may need to lap the valve to the seat.
corrosion on the seat?
debris in your tank?

Put a overflow tube on your bowls so you dont have a fire

TwoTired · « **Reply #3 on:** October 29, 2013, 12:33:19 PM »

Learn to turn off the fuel valve when you park it.

taggat · « **Reply #4 on:** October 29, 2013, 12:34:02 PM »

hahaha cant count how many times of done that.

Sprocket75 · « **Reply #5 on:** October 29, 2013, 12:55:26 PM »

Quote from: TwoTired on October 29, 2013, 12:33:19 PM

Learn to turn off the fuel valve when you park it.

+1 on this!

Mooshie · « **Reply #6 on:** October 29, 2013, 12:58:15 PM »

Maybe some debris caught in the carb (I had this on my #3 carb for the longest time--not there now). Rap the carb bodies with a screwdriver handle to see if that dislodges anything. Turn off the petcock (already mentioned) and I put a small block of wood under my kickstand (when at home) so the bike is more upright and lastly I run the bike for a bit with the petcock turned off prior to parking so not so much fuel in the bowls. I have a CB550

ncstatecamp · « **Reply #7 on:** October 29, 2013, 04:04:41 PM »

Quote from: flybox1 on October 29, 2013, 12:24:47 PM

rubber-tipped float needle? if brass, you may need to lap the valve to the seat.
corrosion on the seat?
debris in your tank?

Put a overflow tube on your bowls so you dont have a fire

Brass, brand new came in a set as did the rest. How do I lap something that small?

goldarrow · « **Reply #8 on:** October 29, 2013, 04:07:36 PM »

Quote from: TwoTired on October 29, 2013, 12:33:19 PM

Learn to turn off the fuel valve when you park it.

then make it a habbit

lucky · « **Reply #9 on:** October 30, 2013, 11:31:29 AM »

Quote from: ncstatecamp on October 29, 2013, 12:15:15 PM

My number 4 carb occasionally leaks, but not a continuous leak. If leave the bike over night (side stand) without turning the fuel supply off I'll get a pool of fuel on the engine, some on the ground. The float height is correctly set, and brand new float stops. This only happens on number 4. I've taken the float stop out and cleaned it (there was nothing on it). Anybody know what's going on?

What that means is that when the bike is leaned over on the side stand that fuel is coming out of the vent line or overflow tube and the vent line is so short or non existent that the fuel gets on the engine then runs overboard.
Do you have float bowl overflow tubes going overboard?

OR... The other thing is that when the bike is leaned over on the side stand, and the float bowl is trying to fill up because the gas valve is open on the tank and the float cannot come because it can get hung up on the edge of the float bowl and won't shut off. So the fuel just keeps running and overfills the float bowl and goes out the overflow or the vent tube.

You should have FOUR overflow tubes and FOUR vent tubes .

The vent lines should run upwards and above the carbs. Then down.

Turn the gas off at night, before you burn your house down.

lucky · « **Reply #10 on:** October 30, 2013, 11:42:44 AM »

Quote from: flybox1 on October 29, 2013, 12:24:47 PM

rubber-tipped float needle? if brass, you may need to lap the valve to the seat.
corrosion on the seat?
debris in your tank?

Put a overflow tube on your bowls so you dont have a fire

If the metal float valve and seat have a step worn into them, all the lapping won't fix it. You have to look at them with a magnifying glass.
Just buy a new needle and seat and be done with it.
That is why HONDA went to rubber tipped float needles so that the engine vibration would stop wearing a groove in the float needle.

Then we learned that the rubber tip needle can get degraded or warped into a non concentric cone shape and leak.

The metal needle and rubber tip needle are different angles and WILL NOT interchange.

Also HONDA went from a solid float needle to one with spring and plunger.
The reason for this was to stop the needle from getting cocked in the seat when the float dropped way down and could get stuck.

By adding the little pin and spring for the float tang to rest on, it keeps the float needle up far enough to keep it from gettin stuck when it drops down all the way.

If you were a mechanic at a dealership like I was, you lived through all of the changes HONDA made you know the reasons.

lucky · « **Reply #11 on:** October 30, 2013, 11:53:10 AM »

General thinking ...LUCKY

Pretend you own the house or apt you are living in.
Would you turn the petcock off at night, or take a chance of a fire?

What about others that could be burned?
Sociopaths (no empathy for others), are exempt from this question. LOL..lol
Don't get me wrong...Sociopaths make good surgeons. LOL..lol

ncstatecamp · « **Reply #12 on:** October 30, 2013, 07:37:16 PM »

As I said before all four are brand new needles and seats. I typically remember to turn it off when it sits more then an hour (though seldom remember to turn it on before I leave...) I had tubes on there but they got taken off and I forgot to put them back on before I left on my trip.

seanbarney41 · « **Reply #13 on:** October 30, 2013, 09:50:40 PM »

put the tubes back on, always turn off your petcock...'nuff said

david 750f · « **Reply #14 on:** October 30, 2013, 10:29:07 PM »

New float valves? Honda or aftermarket?. If they came in an aftermarket kit and you used the float bowl gaskets sometimes the gaskets need to be trimmed. The floats may be hanging up on the bowl gaskets.

Pecantree · « **Reply #15 on:** October 31, 2013, 03:55:36 AM »

In one of Hondamans posts he talks about the float hinge wearing a burr in the float support post.
Causing the float to stick when the bike is at an angle (ie.. side stand)
His fix is to pull float and run a razor blade against the support posts and cut off burr.
Good luck
Steve

Let us know what you find.

+1 on shut off fuel

cougar · « **Reply #16 on:** October 31, 2013, 05:29:26 PM »

+1 on the last post !! Making sure all your vent and overflow tubes are in place is a good point. But that's just redirecting to the overflowed gas to accumulate on the ground, wasting it and still NOT Smart ! Since you've said you've got New needles and seats you need to find out what's causing the problem. Myself I'ld start by checking the seats for trash keeping it from sealing or the float hanging not closing all the way. One other that comes to mind. Do you have brass floats? Maybe one of them have a hole in it and be full of gas. ?? Oh well my thoughts. ...cougar...

tlbranth · « **Reply #17 on:** October 31, 2013, 05:58:12 PM »

check for a dimple in the float tang - can cause intermittent sticking. As a diagnostic, swap floats with an OK carb and see if the problem moves. That's how I found my problem......well one of them.

74750k4 · « **Reply #18 on:** November 01, 2013, 09:20:07 AM »

Those soft brass tangs get dimpled after 40 years, or so. Hard for the needle to move across it as the level pushes up, so it gets caught on the tang, with the float stuck, allowing gas to continue to flow in... +1 among other problems.

News:

Author Topic: Carb leaking, intermittently, sometimes... (Read 2564 times)