Carb leak

[GrimReaper]

 Hello guys,
My left carb leaks now and then.After I take float bowl out and I move the float 2-3 times up and down is ok for a few days and then again.What is the reason?The carbs were rebuild about year ago.Is possible to be stuck needle?
 Thanks

[Ed Miller]

It usually seems to be caused by a tiny piece of junk, like shedding tank liner, getting in between the float needle and seat.  Do you have a fuel filter?

[GrimReaper]

Yes I have but I think to change them.I looked at the one Snowbum recomended from NAPA but they are way too big for my taste

[Mike V]

Where is it leaking from? If from the bowl, check the bowl gasket seating surfaces where the gasket rests and the condition of the gasket for pinches. . Also check your bowl for warpage. You may also have a sticky float needle, try to clear it from any debris and look for wear patterns on the rubber tip of the needle contact. Make sure the float needle connection to the float flang is attached correctly and not hanging up. You may also check your float pivot pin.  Sometimes the float flang where the pin slides into is sloppy and may need to be closed up CAREFULLY with a small pair of pliars. The float needs to move and rotate freely about the pivot pin. Check Snowbum's site he has great directional information there.  http://bmwmotorcycletech.info/bingcv.htm
Also look through section 4 on his web page.
Start by checking the float adjustment - float should be parallel to carb body. Be careful not to leave your petcocks in the "on" position when the bike is not running.

Let us know what you find - you'll get plenty of additional help if I've misguided or left anything out.

[GrimReaper]

Mike I think is not from the bowl gasket.It leaks a lot.like there is no bowl at all.I will let you know when I have time to look at it

[Mike V]

Sin,

If your float needle isn't closing it's probably puking the fuel out of the overflow.

Keep us informed.

[GrimReaper]

That's what I think.Is it possible the needle to stuck in closed position,not allowing fuel into the engine.I had that promlem before.

[Mike V]

I can think of numerous things but I would focus on the operation of the float and the needle valve. The float valve wire retainer may not be assembled on the float tab correctly. I would get a close look at the float components and the operation. You can either remove the carb or leave it on the bike. I would leave it attached first to check the operation of the fuel delivery with a drip pan under the carb. Take the necessary precautions working with fuel, you know the drill, well ventillated area and no open flames. With the float bowl removed, a drip pan below, and the petcock on let the fuel flow freely and gently raise the float upward checking to see if and when the fuel flow stops. This is a good time to check your float adjustment. You'll feel the float valve seat against the needle seat. Careful not to apply too much pressure on the float. There should be a very small plunger inside the needle and fuel should stop flowing when you raise the float to be parellel with the carb body. Also check to make sure the carb is reasonably level with the bike on the cenerstand and not turned too far right or left on the intake snorkle(s).

Keep us in the loop and informed.

[Yikes]

I had a carb leak that was due to junk from deteriorating fuel lines keeping the float needle valve from closing.  Replacing the fuel line fixed that.  I also added a nylon fuel filter that I got from Capital Cycle that has a metal screen filter element, so no flow problems.

Earlier this year, I had a problem with the right float needle getting stuck closed that was due to poor venting through my gas cap.  If your tank makes a hissing sound when you unscrew the cap after you ride a bit, you've got venting issues and the tank is building up negative pressure, restricting fuel flow or in my case, sucking the float needle up into the seat where it gets stuck.  Once the vent holes in the gas cap were cleared, no more sticking.

[GrimReaper]

Thanks guys,the carb that leaked was turned a bit more to the right,but not that much IMO.I put it back.The fuel lines are 1 year old.I will check float adjustment when get back home but first will wait to see if puttin carb in level will cure the problem

[GrimReaper]

Put the leaky carb as much as i can in level(i did not have any tools with me) and on way home start leak again but very slow leak.When got home i leveled it again.Will see tomorrow is it going to leak again.