where abouts did it snap? depending on where it went you might be able to bang a socket on the stump and turn it out or weld a nut on and turn it out or use some stillsons or something?

how did you go about tightening the bolts down, a little bit at a time evenly or cranking one down after another?

I thought it was after 5 posts but maybe its ten?

just post a load of rubbish in the tard farm until it stops the answers are listed somewhere on the site - have you had the impossible spelling of carburettor one yet?

It used to be 5 posts... maybe after that last recent bout of spammers we got, it's up to 10 now It was awful, many posts about stupid crap!

The questions are there to keep spammers and bots off the forum... but I agree, it does make it hard for new people to join. There have been complaints about it on the FB group 

Posts in the Tard Farm are a good idea but unfortunately, they don't count towards your post count

I see GW is up to 8 posts... I'm realllllly hoping the questions stop for him after 10 !!!!

What a real bummer. Similar thing happened to me but it was a cam journal bolt. Really sucks when you are so close to being done.
Are you sure there wasn't a mix up between Newton meters, foot pounds, and inch pounds?
Any chance there was oil on the threads?  Oil on the threads will drastically increase the amount of the rotational torque that is transferred to the stud as far less energy is lost to friction.

Anyways, I think those studs are a replaceable part sold by Suzuki. Am i wrong?
Simply disassemble the head until you get far enough to reach the point the stud broke. Remove and replace it and then start the reassembly process again. Unfortunately you will want fresh gaskets, etc to be sure you dont create a new oil leak.
If the stud snapped at the point where it threads into the bottom end you can use a reverse drill bit and an easy out to remove the studd fragment. The one nice thing about Suzuki using soft metal bolts is that they are easy to drill into, relatively speaking.

Damn sorry to heart that, the bolt could well have been damaged before. I know many folk who will not reuse head bolts. I recently had to change mine on another bike because I kept getting head leaks.

Unless the bolt broke off right at it's base, you could heat up the remains of the stud  with a torch (to loosen any locktite that may be on the base), and work it loose with a vice grip.

Good luck, it's a bummer to have that happen at the last point.

Studs are pretty cheap from Suzuki and seemingly still available

https://www.motorcyclespareparts.eu/en/suzuki-parts/1999-gs500e-motorcycles/cylinder

or the expensive one is in stock here (I think you are UK based?)

https://www.fowlersparts.co.uk/parts/5286103/gs500e-v-y-97-00/cylinder

I'd probably chance reusing the gaskets than replacing ones but you'd probably be doing it right to replace.

If you never started the bike, the gasket should be fine. I'd take a good look at it, if the plasticky covering on it seems OK i'd resuse.

For reference , what type of torque wrnch did you use and whan last was it calibrated? (PS you can check it with a vice, a bucket of water and some maths.)