leaky carb after rebuild

[DeeG]

I rebuilt the Bings on the 45, and now the left side one leaks as soon as I turn on the fuel.  I have adjusted the floats according to the instructions and I even pulled the bowl off, lifted the floats all the way up, and still, it leaks.  

~sigh~

Any ideas?  I would really like to get this thing running again, National is coming up soon and this is the bike I was to ride to Redmond.

[nhmaf]

The float needle itself, and/or its brass seat my either be worn out and not prperly sealing, or there could be a tiny bit of dirt in there that prevents it from sealing.  Or the tiny spring may have gone AWOL?  There is a little info on this in the Bing Carb manual, but unfortunately the diagrams they have of this particular part of the carb leaves much to be desired.

What parts did you replace or clean when your worked on the carbs?

[montmil]

Suspect a bit of trash is holding the needle off the seat, preventing it from closing off fuel flow. Did you check, clean, or replace anything in this area? It's something simple for sure. You may have dislodged a piece of decayed fuel line...

Monte

[dav]

Had the same problem when i put new fuel lines on (our insects friends made a home in them) thought i fully cleaned them out but no. As the others said i reckon its crap playing up with the needle/seat.

Hope you find the problem

[Barry]

Agree that it's likely a bit of dirt if that carb was ok before.

The conical tip of the float needle is some sort of rubber and may get indented over time. Any possibility that the left got swapped with the right during the rebuild ?

Or is it a new float needle and maybe the old one would work better ?

[Bob_Roller]

Where is the fuel leaking from ?

The carb bowl, or the float bowl vent port ?

[Semper Gumby]

Hi DeeG.

A friend had this problem on his R90S.  We replaced the LH float bowl gasket twice!!!

Turned out it was a bent bad piece of fuel hose at the carb fitting that was leaking!!!  (everytime he turned on the fuel)    

Make sure your fuel lines are not brittle and cracked or the ID is not too large.

If your fuel lines are anything less than "perfect", replace 'em.

[DeeG]

I picked up the Bing rebuild kit, #6 in the pic:

http://www.bingcarburetor.com/bmw/bmwcvkits.html

and replaced pretty much everything.  The only thing I didn't do is the butterfly assembly .  When I checked it with the bowl off, it looked to be leaking from the 'hole' that the float needle lives in.    When assembled, it comes out the bowl overflow.

I guess I'll disassemble it again and give it another bath with the carb cleaner.   And I'll make sure that the main jet is in the proper 'detente'.


Grrr..... hope this works, I have two more sets to do.    

[Rob Valdez 79 R65]

Dee, you did not say if you replaced the fuel line, or not.

If you are using the braided cloth, it isn't a bad idea to replace it every 3 or 4 years.


If you did replace the hoses, then it sounds like the needle valve is not seating.

[DeeG]

I'm going to replace the fuel line.  I'd really like to find the braided stuff, just to keep it stock looking, but so far no luck.  I do have the blue line but I just can't bring myself to replace it with that stuff.  It would look great on the blue R75, but on this bike it just looks ugly.  

I think what I may end up doing is going through Aircraft Spruce or one of the other a/c parts houses and getting some plain black line.

[Bob_Roller]

I think Aircraft Spruce, has the Bing alcohol resistant cloth braided fuel line .

Their part number is 05-00500, though, it is blue as well .

[Rob Valdez 79 R65]

Hucky's has the braided cloth, if you want it.  He is fast, too.

http://www.bmwhucky.com/007516.html

[DeeG]

thanks Rob!  

Look at all the stuff, wow......  Bookmarked.  hehehehe

[Rob Valdez 79 R65]

thanks Rob!  

Look at all the stuff, wow......  Bookmarked.  hehehehe

I especially cherish his real, copper, crush-able drain plug washers!

[DeeG]

Well, the bike runs and doesn't leak!  YEAH!!!!

Had a mechanic friend come by and help learn me some mechanical stuff.  

One of the things we worked on was the leaky carb on the R45.  One of his tricks was to hook up a short line of unused fuel hose and blow a bit of air into the carb.  Floats down, air goes through.  Floats up, no air goes through.  Hmmm...on mine, floats up, air goes through.  He pulls the floats off, and looks at the needle.  Then he grabs the old needle.

Ahhh Haa!!!  Bing sent me needles that are not only too small, they are square.  The old ones are triangular.    I could have kicked myself, but, it was something I never thought to compare.

So, got the carbs hooked back up and he spent some time fine tuning them.  Bike has NEVER run better.

 

So, I'm going to send them back, and get the correct ones.  Then I'll do the R75, and he has offered to come by and finish both bikes with his 'carb sticks'.  What the heck are carb sticks?