Hello there!
One of the hoses from the petcock has started leaking gasoline, not much but not a few drops either.
It seems that is the one to the side of the on/res/pri tap.

Some pictures:

This is the hose (the one with red tap), it wasn't connected to anything, just dangling on the other side. I put it on this side because is not near the exhaust.


This is the close up of the origin of this hose I think(90% sure)



For now I plug it when I park the bike but is not a solution. What can I do? Is the petcock broken? Something is wrong with carbs?
Thanks in advance for the answers and sorry for my not so great english.

The tap is set ON in the picture. Do you *run* the bike with ON or PRI set?

Your fuel tap looks a little different from mine, but one of the following is probably not connected.

- Main line from tank to fuel tap
- Reserve line from tank to fuel tap
- Vacuum hose from fuel tap to carburetor

By size, and the fact that your bike goes, I want to guess vacuum hose. Do you have somewhere you can remove the tank and see what's hooked where, verify the hose is from the fuel tap, then compare with a diagram?

For all I know it's possible to feed fuel from the tank via gravity with switched hoses. I don't imagine that would be a stable situation. Also can't say from pictures whether your tank's main or reserve fuel port is plugged up. People do funny things to their bikes to work around perceived or real problems.

Could also be either the airbox drain or the fuel cap well drain. These should exit on the RHS at the back of the motor. Your model should have three hoses here. The third (thinnest) will be the battery vent. The one with the cap is from the airbox.

It couldn't hurt to double-check that all the hoses are hooked up properly. These (corrected) diagrams have helped me and many others over the years!

http://wiki.gstwins.com/index.php?n=Main.HoseRouting

Algrith let's answer some questions

Quote from: wilee on February 23, 2019, 01:50:41 PM
The tap is set ON in the picture. Do you *run* the bike with ON or PRI set?

The bike does run with the tap on the **ON** position

Quote from: wilee on February 23, 2019, 01:50:41 PM
By size, and the fact that your bike goes, I want to guess vacuum hose. Do you have somewhere you can remove the tank and see what's hooked where, verify the hose is from the fuel tap, then compare with a diagram?

I could try removing the tank and take a look at what's going on, will do fo sure

Quote from: Sandgroper57 on February 23, 2019, 04:51:12 PM
Could also be either the airbox drain or the fuel cap well drain. These should exit on the RHS at the back of the motor. Your model should have three hoses here. The third (thinnest) will be the battery vent. The one with the cap is from the airbox.

My bike is a 2003 one if I am not mistaken, I've checked the other side and I have both the airbox drain and the tank vent(I think). The battery one is missing but I've checked really quickly, I'll take a more in depth look tomorrow

Quote from: ShowBizWolf on February 24, 2019, 02:04:13 AM
It couldn't hurt to double-check that all the hoses are hooked up properly. These (corrected) diagrams have helped me and many others over the years!

http://wiki.gstwins.com/index.php?n=Main.HoseRouting

Will do for sure!

Also I've noticed that the more fuel is in the tank the more it leaks

Finally got to look at the pictures on something that isn't a phone.

It seems the fuel valve is no longer functioning properly.  The line identified appears to be the vacuum line which normally does not see fuel at all and should be connected to a carburetor.  In the "ON" position, the carbs will not get fuel until the engine is running when the valve is functioning properly.  This is controlled with the vacuum line.

The increase in leaking fuel in proportion to the amount of fuel in the tank is an indication that the fuel is going directly from the tank to the line in question.  This should only occur with the valve in the "PRI" position and the line going from the valve to the carbs.

Alright alright, sorry for the late reply, I've been busy with other things.

I've resolved the issue: the leaking hose was the vacuum hose which for some reason wasn't connected to the carb (the bike run though).
Checked the hose routing, all good except I am missing the battery vent one. Will get one soon.
About the petcocks : the frame mounted one: toasted, basically was in "prime" even in "on" or "res". I have changed it and now it's all good. The tank mounted one: also toasted, when I turned the screw to "on" after changing the fuel lines the screw started pissing gasoline. Changed this one too.

The bike now is runs fine.