1974 R90/6 Bing 64/32/11 will not stop leaking fuel.

[dieselyoda]

I'm doing this for a friend who has passed and want to give it to his children as part of his legacy.

One carb, won't stop leaking fuel.

New float and needle, float set right???.

The needle has the ball in it and the floats are parallel to the body with the ball compressed.

Seat, not replaced but has been cleaned thoroughly with a soft gallery brush. I see no particular issues with the seat and the needle seems to be good.

What am I missing?

 

[20774]

With the carb bowl off on the offending carb, can you shut off the fuel if you raise the float carefully with your finger up to the parallel position? If it shuts off that way, then there's something that hinders the smooth operation with the float. You could try some toothpaste on the eraser of an old fashioned pencil and use it to lightly burnish the seat to be sure there's no physical damage to the seat.

Have you taken the float off and put in a jar of fuel? The float should sit such that 1/3 is above the fuel line. If the float sinks, that would indicate that the float has gotten heavier and needs to be replaced. Edit...you said new float so guess that's not it. You could swap floats left-to-right and see if the problem follows the float.

 

[James.A]

Another possibility would be the float bowl itself. It is not unheard of for the overflow tube to be cracked or otherwise messed up from water in the gas freezing and splitting that little brass tube. This is why we should empty the float bowls and leave them off during winter storage.

 

[dieselyoda]

Great advice but now I'm stretching.

Filled the bowl full of fuel, careful not to go over the overflow tube. Placed on a dry towel and it's wet?

Porous bowl? Cracked from water as previously mentioned?

I loved the toothpaste comment! Used it many times to confirm good valve and seat margins on diesels.

Sucks when you realize you forgot more than you rememberrrrrrrrrrr..........what was I about to say?

 

[20774]

They make dye penetrant fluids which will seep through cracks and leave a red line where the crack shows up on the surface. Something like that would show you where the fuel is leaking.

 

[swall]

Yes, Magnaflux Spot Check penetrant. Available at welding supply stores. I have also found the developer to be usefull in finding oil leaks. The developer is a white chalky substance that will cause the residual red dye to "blot" out of a small crack and cause the crack or porosity to become more visible. In much the same manner, it will make an oil leak more visible.

 

[ksdcr]

Following this thread, as I like to see how it gets resolved.

Wondering, that if the offending part is porous, what can be done to correct it, short of replacing the part.

Would a a quality epoxy, be effective?

 

[20774]

Can't imagine a coating that would work or survive this situation. Best bet is to just replace the bowl.

 

[dieselyoda]

Not the bowl, tried different solvents and gasoline, full to the top of the standpipe.

Toothpaste trick worked OK. Still get about two/three drops of gas overnight. Gonna repeat it.

Twas a very nice idea. Glad the BMWMOA reminded me I forgot to renew.

It's a pretty old bike and in my Airhead days I had the muscle memory to turn the petcocks off if it was going to sit for more than a few hours.

I might be, thinking I am, getting a bit cranky and having expectations that just not be reality. I do work with Gen Z's that won't get out of the service truck to put a track on in the rain, or snow, if there is a cloud or it's too close to quitting time.

But, there was that time, 300 or so miles in the rain. The boys had a very nice fire going when I got there. I was pretty cold.

Kicked the fire and my boot went "KABOOM!"

Wet was an understatement after I ran into the lake.

 

[melville]

Ummm, I have no expectations of not leaking if I don't turn the taps off. Always off when parked!

 

[kbasa]

I'm doing this for a friend who has passed and want to give it to his children as part of his legacy.

One carb, won't stop leaking fuel.

New float and needle, float set right???.

The needle has the ball in it and the floats are parallel to the body with the ball compressed.

Seat, not replaced but has been cleaned thoroughly with a soft gallery brush. I see no particular issues with the seat and the needle seems to be good.

What am I missing?

If you have ethanol fuel, check that the fuel lines aren’t all saturated and dripping fuel. I just went through this last week. It took a bit to notice that the fuel line itself was saturated. Don’t forget the crossover.