Leaking carburettor 912

Thanks for the replies

The floats are the new models and only a couple of months old. They float free and at the right level. I have checked the armature height it is correct and matches the left side which doesn't leak. The fuel pump was replaced recently as part of the 5 year rubber cycle and the leak has not changed pre or post these measures. 

I am going to check for debris and have some surgical magnification loops and light  and will check further will and advise.

Regards Ian

I had the same problem. Complete Rework on floats, valves, every rubber part did not help.

I got the hint to check the valve seat and found a tiny breakout.

This was not visible with a magnifying glas, it needed a microscope or as you see a camera with a good macro lens.

See attachment

The valve seat can be replaced, just drill an M8 thread into it (or close by imperial) and pull it with a screw and some washers.
Replace with new with some Loctite.

My carb is completely dry since then.

Dear Steffan,

Thanks for your reply-having rechecked settings etc and using Carburettor clean and compressed air to make sure there is no foreign material I still have a leak. I have decided it is the seat as only one carby does this and it didn't change with the rebuild kit. Thanks for your suggesting of how to go about this as I was wondering how to go about this. 

Thanks 

Ian (Australia)

Dear Ian,

replacement is really easy, just use a press oder a drill stand or something under good control to press in the new valve seat.

The Bing partnumber for the valve seat is: 51-536/15 

If you can't get it in Australia, say a word.

Dear Steffen,

Thanks for that and the part number. It will probably be a week or two till I get to it and I will let you know.

Cheers Ian