It happendens to me altso last year, in my last autum ride.
Soo its becuse of this it was my last ride that year, in any way I did manage to get home!
At first the engine seems to be slugisch, nemas problemas, its often low gas, turned on reserv, stopped at nearest gas station, filled up and back to normal on the petcock!
In any case the engin started and I got home, even if it feldt like one is short of fuel!
To that.. Im alredy read a lot of the vacum petkock isue and thougt its about this?
Next wekend.. knowing about the vacum petkock isue, turned the petkock to overide the vacum and fill upp like no vacum need!
Than.. there was no current in my batteri, it was totaly broken!
Reading a lot in this forum, asking my biker friends and then I boght me a new AGM batterie.. mostly becuse my biker friends and some on this site says that AGM is often better then ordanary wet bateries.
In any case.. it was a menace to replace it, a lot of screws to be lose and side panels to.
On the other case, when the new batteri was in place, the engin started on standard petcock in its normal standing.
And to the petckock isue, I figure out there is several differant issues, no perticularu for our bike.
First, its a vacum petkock, there is a vacum tube frome the carburator to the petckock to make it open, this one can be old and leaking and it can be lose!
Any petkock have some filter to it, and if its full of dirt, it dont provide that much petrol anyhow.
Then try the reserv position, it sholdnt make it better, the same filter, but lower part on it!
In my case it was the battrey, that was broken.