Join Date: Oct 2013
Location: Chilliwack, BC, Canada
I doubt that welding is an option as carbs are usually a die cast combination of aluminum, zinc and marsupial spit. If it doesn't meld into a blob, I'll be surprised. Haven't tried heat repairing a bike carb. in decades so may be different materials.
Were it mine, I'd use some Devcon or quality epoxy to form a new end after grinding away any displaced metal. Trying to bend carb. material back into place generally results in breakage, IME. I wouldn't bother trying to join any more metal to that end because Devcon or other good epoxy will form a strong area. It will be much simpler to line bore the new hole in line using the other as a pilot if you are boring through epoxy than boring metal, especially if the hole is bored across a joint of metal and epoxy. In that case, the drill will usually walk into the epoxy and make an out of line hole.
Once you have the pin inserted and needle valve seating, set the carb. fuel level by using a clear plastic hose off the carb. drain. That will show the actual fuel level and allow you to adjust for any variations in position of the pin.
I've fixed some carbs. in this way where a passage plug had to be removed or the like.
An alternative is to drill and thread for a screw to come in beside the pin and trap the pin between screw head and post. That requires some precision drilling and threading but not too bad as the die cast is easy to machine. That will duplicate the manner of holding which is used on many chainsaw and other diaphragm pump carbs.