Out here, this can be the bane of any CX or carby BX owners life; it's fine particles of black muck that get stuck in the jets of the carby.
The cause I've heard as being the material the fuel lines plus in the case of the BX, also the material the tank is made of being a black plastic type that begins to degrade with age and washes off as minute particles which are hard to detect with the naked eye but large enough to build up in the jets and bowl.
The other explanation that Shane gives is that they originally had a filter back near the tank somewhere which could be correct also, but something I've never found so it may be that my cras have all had them removed.
To effect a permanent cure, take the 4 nuts off the top of the black plastic elbow fitted to the top of the carby and if you shine a light down between the two throats of the carby you'll see 4 jets hiding down there and that's the problem child.
Slacken each with a flat bladed screwdriver and with either a pair of very fine small needle nosed pliers or a pair of foreceps, remove them one at a time, blow out with compresswed air, blow the air gun down into the hole they come out of (trying not to get a face full of petrol in so doing) and refit. One of those cheap $80/$100 Chinese compressors doing the rounds are ideal for this kind of job. That cures the problem. Now to rectify the cause:
Go to the local parts place and buy a filter of the variety used in EFi cars; the metal variety with a bit of volume about it.
NOT a Ryco plastic throwaway variety. I have found one for a Subaru Forester is ideal, and fit it into the fuel line just before the fuel pump. These are around 5 - 6 times the capacity of the throwaway variety. In extreme cases, I have fitted a Commodore V6 type which would be 10 - 12 times the size of the Ryco. Then if you want to be 100% sure that the problem will be substantially reduced or removed, get a glass type with a removeable and replaceable cartridge and fit that between the pump and the carby.
There's every chance that you will have a repeat of the problem within the first week of fitting this filtration set up and as it occurs, the carby clean out job as I've described above must be done in total to remove the problem; there's no shortcut. You can of course do a full dismantle which is a fairly long job and entails such little gems as removing circlips so small as to almost needing a magnifying glass to see and wire clips not much larger than human hair, which is why this is only done as a l;ast resort.
A word of warning; be extremely careful when removing the jets that they aren't dropped down the carby throat and please don't ask why I'm a bit paranoid about this. :crazy: :crazy: :crazy:
Alan S
