G'day people im Tony & new to gstwins, but have been reading stuff for a while now on this very helpful site.
Well a couple of weeks ago i got my 07 gs500f, its run in & runs quite well by day but at above 4k at night after 10/15 mins of riding
it feels like its running out of fuel. So i know a bit about bikes but that was 15 yrs ago & where 2 strokes.
     If someone had some things i could try that would be great. I have not done anything, its all stock.

Welcome!

Is there something crawling up the carburetor floatbowl vent tube at night, thinking that's its home?

Switch the frame mounted fuel selector (left-hand side; PRI, RES, ON) to PRIme.

Make sure the fuel tank shutoff valve (underneath the tank on the left-hand side) is directly in line with path of flow; if it is not, it will restrict flow enough to cause your symtoms.

 Hi scratch, i,ve tryed all that & a couple few nights ago with no change. But im going to fuel it up next time with regular unleaded 
which is 92 ron (octane) , i've been using 98 ron  can only try it out & see. I've turned the mix jet out to 3 turn
as well, just have at try it now. mate.

does it clear up(more power )above 6k???

Hmm... at night - colder, denser oxygen...

Is it hesitating?

If so, moving the clip on the needle lower should clear that right up! 

My bike used to act up at night. Except, that was because homeless people kept jacking one of my spark plugs to use as a crack pipe. 

Yes it comes good if ya give it some more throtle but then when you go back to cruise its back to the same thing. I'll give the needle bit more on my days off. Thank heeps 4 ya help guys. will let ya no in a fuw days.

S6

Wrecent?
I think, your thinking, what I am thinking haha. Does it only run rough with the lights on? I am not gonna jack this, you got there first 

[4

Hehehehe.  Yeah, my first thought when I first read this thread was, "lights...but it's a motorcycle, the lights are always on...."  I gave up, because besides that, there should be no difference. 

Seconded on taking it to the dealer.

Bugcool is on Oz` and we are waiting to find out from him if daytime lights are mandatory there. From what I have seen in all the Cheesy daytime Australian soaps we get here on UK Tv ( and the Mad Max movies  )I dont think they are but I will stand corrected. Like you guys I am thinking  it could be electrical and the problem is not so much related to the fact its night but that the lights are on.
The bike should be under warranty given its age.....so yeah it should be the dealers problem.

G'day guys, yes lights come on & theres no off switch, i've booked it in to the dealer next week, he is going to put a sniffer up its bum to see if its lean.

Being that you in Oz, its likely that you picked up some dodgy fuel I had the same problem when I went to Tassie as did the other bikes that went with us and I have friends up here is Sydney including myself get bad fuel its pretty common thing to happen although you wonder why in this day and age then you remember that all the oil companies and service stations are trying to rort us so you thank god you bought that old air cooled bike that will run with dodgy fuel and not that new sports bike that your friend got that wont even start with the dodgy fuel and regret not getting a docket when your bought fuel from that dodgy service station so you can make him pay for the carb strip down and clean

  All is good now, the dealer put 135 mains in & move the needle up & adjusted the float to 13mm. I road home & it was great, had more go & picks up revs better. Tonight i'll be giving it a good test on the way home from work, there are some nice long stretches of freeway, so will let you know how it go's.

  It runs very good now, so it was just lean.    to everyone for ya help.