Quote Originally Posted by stefan.golinschi View Post
Hy! can you tell me what a gas cap vent is?
The vent's primary purpose is to allow air inside your gas tank, as fuel is being removed during engine operation. If the vent is not working, a vacuum will be created in the tank and fuel will not easily flow to the engine.

If your bike can idle in Neutral for several minutes, with you increasing/decreasing the RPMs up and down, it probably won't be the vent. But if it dies shortly after starting (which just also happens to be when you try to move forward), the vent is a good first consideration.