Motorcycle Repair: Carbs, vent tube, bench test

Question
QUESTION: Hi; I have a cb750c 1980 Ireplced the float Needle valve it does not shut off the fuel?, also what jet goes in the needle jet holder the 102 or the 68? Thanks God bless

ANSWER: the larger jet goes in the main tube that holds the needle.  Did you use Honda needle valve or aftermarket?  Aftermarket valves are notorious for leaking.  You did replace the seat and the valve, right?  Let me know,  Jan

---------- FOLLOW-UP ----------

QUESTION: Hi; N0 the carb set ia after market/ No i did not cange the seat how do you get the seat out? there is no hole in the back of it to punch it out?
The carb set is made bynapco japan.I take it the large jet is the 102 or the 68? god bless thanks

Answer
Sometimes the seat is screwed in, sometimes it is pressed in.  Be sure to clean the seat innner surface really carefully, and ensure there is no debris or old fuel in the system.  Yes the 102 is the larger jet.  Good luck,  Jan

P.S. I always bench test carbs before putting them back on the bike.  Check that your vent tube in the foat bowl doesn't have a crack in it, popular mistake to make and lots of needle valves have been replaced unnecessarily because of that fault...