Just came home from a spin on my gsxr400 and noticed oil on the left hand side fairing. It seems to be coming from the head gasket.
Can/should I tighten the head more to stop it leaking?
can I loosen then re-tighten the head and pop some sealant in there?
Is it a big problem/should I stop riding the bike?

The bike sounds/and seems to be going fine. Only owned it since yesterday so am not too pleased

If I were you I'd get the fairings off, clean the bike down thoroughly especially the engine and then run it to see exactly where the oil is coming from. My advice would be not to use sealant and gasket goo. If there is an oil leak it my mean that something is loose or warped and you should address that problem at the root.
Let us know what you find when you've cleaned it off.

Thanks mate. I'm gonna leave it to a mechanic as things just got worse. I had oil this morning went to the gym and back, about two mile, no oil? The leak is very small and the bikes not covered in it. I'm very confused?

I just checked the oil(see post above)and it was nigh on empty. I checked it before running the engine, empty(well below the glass, had to lean it towards me to see any). I ran the engine for a couple of minutes, checked it, empty, checked it again in a couple of minutes, empty. Topped it up, fine. Took it out for a short ride and now there's too much?
Am I doing something wrong?

Also, the exhaust/end can seems to stay hot for ages after riding it. Is this normal?

If you've run the engine then you'll need to leave it at least ten minutes maybe more before any decent quantity of oil is going to show in the sight glass.

Like I said, I checked it before I started it up and it was empty then, it was not running for about three hours? As you can probably tell, I'm pretty dense when it comes to mechanical stuff, but even I can't mess up checking the oil.

p.s. Thanks for the help, I'm really lost and need it.

When you top up the oil the bike should be standing up straight not leaning over on the side stand as this will give a false level and you will put too much in. The leak is more likely to be coming from the rocker cover gasket than the head gasket.

Thanks. I'm gonna get the mechanic to look at it as even if it is easy enough for me to fix it's so wet and miserable here and I don't fancy getting piss wet through.

If you need a rocker cover gasket I have a new original one still in the packaging.

Nice one. The mechanics got it at the mo, but I'm sure he'll ring me if it's needed.