I have a 1980 XS400 that has been parked for some time because it will not stay running. About a year and half ago it began leaking fuel out of the air cleaner on the left side. I assumed this was due to a bad/dirty/sticky valve in the carburetor. After several attempts to clean and replace the valves myself I ended up taking the bike into a shop. Although they had no desire to work on a bike so old, they did get the carb to stop leaking (although they did not address a number of other issues we requested).
Around the same time (shortly before if I recall correctly), the bike started to die after a short time of riding. I assumed that the issues were related, but now that the carburetor is no longer leaking the bike still dies after a short time.
This week I setup the following experiment to try and find out what is going on. I mounted a small test fuel tank and ran a fuel hose to the carburetors, substituted a stable power source in place of the current battery, and ran some clear tubing from the bowl drain holes so I could monitor the fuel level in each carb.
After adding fuel both carburetor bowls filled to 3/8" below the gasket line (a bit high according to the manual). I started and ran the bike and the fuel level remained constant. It ran okay until the fuel in the tank was exhausted at which point it died. By adding a small amount of fuel, I was able to get the bike to restart and run.
Am I correct in assuming that this indicates that the problem may lie in the tank and/or petcock?
Also, the bike would die as soon as the fuel in the line was exhausted - the level in the carburetor bowls did not go down at all. Is this normal? I would have expected the bike to continue drawing fuel from the bowls for a while before dieing.
Unfortunately, I have some theoretical understanding, but not much practical knowledge. So any assistance would be greatly appreciated.
Around the same time (shortly before if I recall correctly), the bike started to die after a short time of riding. I assumed that the issues were related, but now that the carburetor is no longer leaking the bike still dies after a short time.
This week I setup the following experiment to try and find out what is going on. I mounted a small test fuel tank and ran a fuel hose to the carburetors, substituted a stable power source in place of the current battery, and ran some clear tubing from the bowl drain holes so I could monitor the fuel level in each carb.
After adding fuel both carburetor bowls filled to 3/8" below the gasket line (a bit high according to the manual). I started and ran the bike and the fuel level remained constant. It ran okay until the fuel in the tank was exhausted at which point it died. By adding a small amount of fuel, I was able to get the bike to restart and run.
Am I correct in assuming that this indicates that the problem may lie in the tank and/or petcock?
Also, the bike would die as soon as the fuel in the line was exhausted - the level in the carburetor bowls did not go down at all. Is this normal? I would have expected the bike to continue drawing fuel from the bowls for a while before dieing.
Unfortunately, I have some theoretical understanding, but not much practical knowledge. So any assistance would be greatly appreciated.