Motor seized when starting cold - please help

[interfuse]

Is your petcock operating properly? When set to "ON" without vacuum no gas should come out. They are prone to failure and will cause gas to force it's way past the floats.

[AlanDog]

Is your petcock operating properly? When set to "ON" without vacuum no gas should come out. They are prone to failure and will cause gas to force it's way past the floats.

Okay, my setup is I have the 4 carb assembly off the bike, and I have a tube clear tube connected to the fuel inlet line.

I add fuel to the line, it leaks out the bottom of the carb. Shouldn't the float valve be able to prevent any fuel from leaking? Or are these carbs simply prone to some fuel leakage, and that is accepted as normal (thus you'd never run them without a vacuum petcock)?

There is a carb rebuild thread in the gixxer.com forum that says this test should work--the carbs should be able to prevent fuel leaking...

The one thing I need to try is with the carbs on the bike, as the slight angle towards the engine intake will affect the float bowl level/float valve sealing.

Thanks, Alan

[Chris H]

Like interfuse say's leaking tap can cause problems but the float valve should not allow fuel through with a simple pipe fitted.
You need to check the float heights and if these are correct then the actual float valve.
If all seems ok then look at o'rings and or possible cracked body.

[AlanDog]

Chris, thanks for the help. I am trying to troubleshoot step-by-step (but I do think my vacuum petcock is working properly. The carbs were dripping gas in the 'hidden' prime position, but they did *not* leak when the vacuum petcock was in the 'on' position).

So I tried using the old float valves, not because I thought they'd work, but just for the sake of being able to say I tried everything... well the two carbs that were leaking do not leak with the old valves. The new valves in my rebuild kits had nice springy tops, apparently they don't press up and seal with enough force when the float is up. So it was my new parts... anyone else ever have this problem?

So now the carbs, positioned on the bike, don't leak when fed into the fuel inlet. But this is with the float tabs bent all the way down (ie the float height as high as possible). So now I need to go back and try to get them to hold fuel with the correct float height. But they've held fuel back for about an hour now, so it seems to rule out more serious problems like cracks in the carb body and it looks like my o-rings are good. Whether I can get these running with the old float valves or will have to buy new ones, not sure. Any recommendations for source of carb parts? I used carbkitscapital.com. Should I buy the OEM float valves or are they the same thing?