I have repaired a couple sets of Keihin carbs with broken fuel screw housings by hacksawing away the damaged carb fuel screw surrounding metal and then using epoxy and a short piece of Aluminum tubing that has been drilled and tapped for the fuel screw (fuel screw, spring, o-ring assembly.) This fix worked very well and was cheap. Sometimes steel springs get rusted into this housing or screws are so corroded into this area they cannot be removed. Also when rebuilding carbs their are 2 other holes adjacent to where the tip of the fuel screw comes through that need to be cleaned with a needle / spray. The three holes are visible when you move the throttle flap. Broken out aluminum at the jets can also be repaired with a piece of aluminum cat food can and epoxy.
I have repaired a couple sets of Keihin carbs with broken fuel screw housings by hacksawing away the damaged carb fuel screw surrounding metal and then using epoxy and a short piece of Aluminum tubing that has been drilled and tapped for the fuel screw (fuel screw, spring, o-ring assembly.) This fix worked very well and was cheap. Sometimes steel springs get rusted into this housing or screws are so corroded into this area they cannot be removed. Also when rebuilding carbs their are 2 other holes adjacent to where the tip of the fuel screw comes through that need to be cleaned with a needle / spray. The three holes are visible when you move the throttle flap. Broken out aluminum at the jets can also be repaired with a piece of aluminum cat food can and epoxy.