Thevacuum passage (see the brass tubebeside the right-hand phillips head screw inthe photo) is blocked - I don't know what with. I suspect that carb had water in it at some stage so it could be corrosion. I've resorted to all the no-no's like poking thin wire down it, trying to pull it out with pliers (which is why it looks a little damaged!), but its solidly fixed in place.The wire will only go in about 3/16" - 1/4".Carb cleaner won't do it.I've checked the "How to" and other forums, but no go. HELP!So, can anyone tell me:
[ul][*]how to clear the passage, or[*]where the other end/s of the passage are (it seems to have more than one outlet - I haven't been able to track them all down), or[*]how the brass tube is fixed into the carb, or where any jets or holes are, anything that gives me a clue as to what shape thetube or passage/s is inside the carband what curves or bends the passagetakes. This may give me a better idea as to an effective way of attacking the blockage, or[*]anysafe (to the carburetor) ways of dissolving corrosion, or[*]any other useful info?[/ul]
Your help much appreciated! Its driving me nuts.

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If you can find a VERY SMALL drill bit, you can put it in there and spin the drill bit by hand with light pressure. Then carb cleaner, then air, etc. DON'T EVEN THINK about taking a drill to it, though.

If one of your carbs is clear, maybe stick the drill bit in there first and mark 'how far down' it's supposed to go, so you know how far to try to get into the dirty one.

I'ver never heard that you can pull it out with a pair of pliers.

 

Brilliant!!!! Haven't fixed it yet, but thanks for the inspiration...

I couldn't find a drill bit small enough (the visible hole is about 1mm dia.) so thought I'd try the tip cleaners from an oxy-acetylene set (must remember that for future!). Found that in both a good carb and the blocked one I could get the smallest cleaner (0.4mm) down only about 2 mm (so much for my estimation of 3/16" - 1/4" in my first post).

I guessed that somehow I must be able to see 2mm down inside a 1mm hole to whatever was that was stopping the tip cleaner going any further in the good carb, so I used my wife's dissecting microscope (every home should have one [wife with a dissecting microscope I mean]) to have a look. Bonza! The brass jet narrows down to about 0.3mm dia at about 2mm from the top. I definitely don't have a drill that small, and can't make any progress with very fine wire (wire brush wire is about 0.3mm, which I've found, will just fit down the vacuum passage in a good carb) so will try to find one!

Thanks for the idea, Gogar.

 

Tell ya what, Gearloose.

.3mm = .0118 inches, which is usually the high "E" string from a set of electric guitar strings. CHEAP AND EASY, MAN.

Or, just buy a .011 and you can even get down all the way to .008 (really small), costs about a buck apiece.

 

Great! Will try to get one tomorrow! Thanks!

 

GOGAR IS THE MAN! I couldn't get a 0.3mm steel guitar string - instead got a .013" (0.33mm) and a pin vise, fitted short length of string to the vise, used an oilstone to grindthe tip to a sort of chisel (microscope helps avoid guessing) and a bit of a taper on the string, then drilled my way through the crap that was blocking the hole.Took about 5 mins drilling, so whatever was in there was reasonably solid. Used a Mityvac vacuum gauge to check the flow through the drilled out hole, found it very similar to the good carb! FANTASTIC! Thanks!

 

Sweet. Congrats.

If you go to a music store where you can buy single strings, you can buy a .011 and avoid buying the whole set and making a .013 smaller. But glad to hear everything worked out!