Carburetor Rebuild Tips

“”My Bing rebuild kit arrived and I am having trouble removing the old slide needles from my 83 R100RT. Any advice on this and other Bing carb rebuild tips?””

There are two basic types of needle mountings. One type uses a captive hidden clip, and the other type has a screw that has to be loosened.

If you have to, use a pair of pliers and protect the needles with something like thin leather at the pliers jaws. BUT you might be able to remove the needles with clean and dry fingers or try soft thin leather gloves or kitchen plastic gloves. ROTATE the needle 90 degrees as you pull slightly downward, then repeat, until needle is removed. When replacing the needles, the same 90 degree rotation, with small upward pressure, is needed for each notch of needle adjustment/replacement. When done replacing the needles to what you think is the ‘correct notch’, be SURE the needles stick out of the bottom of the slides exactly the same amount…use a vernier caliper.    I like to record that value. Mention of needle position is very commonly done by ‘notch’ number. The uppermost notch on the needle is

#1, and as the needle is adjusted to be higher and higher in the slide, the numbers increase, per notch, to #4.

Some needles, probably from about 1985,  were made out of aluminum and the needle grooves (notches) tend to wear rather quickly. If the wear is high, that will allow the needle to be in the wrong position vertically; it can move up and down a LOT. All needles, aluminum or steel, will also wear on their sides, as does the associated needle jet.    The needles are purposely free to move a bit angularly sideways, so normal vibration wears them, and their associated jet. Always replace needle and jet together when overhauling.

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