Motorcycle Repair: 1918 CM400 Carb leaking, brass tubes, cm400

Question
My carbs started leaking from the drain tube on the right side.  I cleaned them and installed new o-ring, now there is gas leaking from the two brass tubes that come out of the side of both carbs. The tubes have two holes in them so I guess this is their purpose.  I hope that this is  clear enough so you can help me.  Thank You, Jason.  

P.s. I changed the needle jets, to the ones that were in the kit.  They looked a little different that stock,  could this be it?


Answer
Well 1918 is a little before my time but I'll give it a shot.  You're right those two brass tubes are the overflow tubes that prevent the fuel from getting into the cylinders if the floats stick.  The problem is that the floats aren't shutting the fuel off when they reach the proper fuel height in the bowls.

This could be caused by a couple if things.  It could be the floats are not adjusted correctly and just set too high.  You need a float gage or a caliper to set them to the factory spec.  If the setting on the floats are correct, check to see if the needle or seat are dirty or the fuel lines are letting rust or dirt get down to the seats.  Also check to make sure the floats aren't bent or something that would prevent them from moving up and down freely so they can shut the fuel off.  

I usually just take the float bowls off with the carbs still on the bike and manually raise and lower the floats to verify they will shut the fuel off when the needle valves are seated.  If they will shut the fuel off, it's probably a float adjustment.

Good luck
Rich