Motorcycle Repair: fuel leakage, worst case scenario, fuel leaks

Question
My wifes 1982 Kawaski LTD 440kz twin cyl. has
a  internal fuel system leak.When the bike sits
fuel leaks into the cylinder .The following has
been done .
1)Carbs have been removed & cleaned
A) Float heights checked
b) floats been checked to make sure they float
in fuel
C) Replaced the needle valves
D) Still same problem
  
One thing that has not been checked is the fuel
cock diaphram. My thinking is the needle valve
should hold?
Any ideas!          Regards,Kevin

Answer
Kevin, looking at the online microfiche, I have to ask if you replaced the o-rings on the float valve seat assy? If not, you can get a fuel leak past the o-rings, even when the needle/seat are shutting off correctly.

In a worst case scenario, you can take the carbs off and hang them over a pan, connect the fuel line to them and watch to see where the fuel is coming from.

The petcock has a 4 hole gasket at the lever, which can fail, and I have found on Hondas that the back side of the selector lever gets etched and will leak even with a new gasket.

The diaphragm for the back side of the petcock could be a source if it is failing, too. Could be dribbling fuel back into the intake port that way. Check the vacuum line into the connector. If it is wet with fuel, that sounds like the probable source.

FYI: http://www.powersportspro.com/partsfish/login.asp

Bill Silver