I got my bike last summer, it worked great for me for most of the summer. It had very low miles about 5000 ( I haven't looked recently).  I went to change the oil last summer and discovered there seemed to be very little oil in it, and I know how much should be in it.  Well I changed it anyways and since then it has been throwing oil out of the main seal on the right side.  And since then it has lost most of it's low end torque and after it has sat for a few days it acts very funny.  I try to move it and it's really stiff like the clutch is still mostly engaged.  Also when I ride it for a long times at higher speeds 65+ it overheats.  So it was the end of the season and I didn't have time to deal with it as I am a college student.  But now that the riding season is comming back in Minnesota, I want to get it working right again.

So I guess my question is this:
What kind of damage can be caused by very low oil?
I read somewhere on the forms about the oil vent getting clogged and this causes the oil to become pressurized and it forces itself out the seals, would this cause the lack of torque and problems after sitting for a while?
I am mechanically inclined, What things should I look for to start diagnosing my problems?

Thanks

If your mechanically inclined you should know that low oil levels can cause untold amounts of stress damage to almost every part of your engine.  Fortunately it would probably have to be insanely low for that to happen with a GS engine unless you went balls to the wall with it or drove it a lot with low oil
2. I overfilled once and it forces itself to a stable point  not a big deal unless your really overfull then it'll kil performance.  I'm not super familiar with bike tranny and clutch setup on a bike so your guess is as good as mine but I'd say it's oil related 
Drain the oil if it's metallic you've got real problems otherwise replace the seal that leaks and fill her back up with fresh oil see what happens then.  a new filter never hurts either

If you're loosing your oil out if the ride side crank seal, that means that the engine oil is getting onto the ignition pickup. You're probally losing power due to a weak spark because of that. make sure it isn't the oil pressure port either, that's an easy fix though, buy the right bolt and plug it

I'm not sure how hard it is to replace that seal, but I think you can pull the ignition, pull the clutch cover, then have acces to it, shouldn't be too hard.

As far as low oil, if it's pretty low, you overheat and it's bad. If it's really low, then you get oil starvation and your engine siezes. Then your engine is shot, you're lucky if you can re use anything in the engine.

In the meantime use 20w50, it'll leak slower and if you've already overheated a few times, your clearances are probally a little larger than original.

No, you aren't mechanically inclined. It's okay though, we're here to help. 

Like I said until very recently everything I did was on cars so I'm still scaling things down!!!   But yeah anytime you need help this board is awesome I've found many answers to problems on here.  Mostly from when my dumb ass rebuilt my carb and lost the vacuum cap o-rings,  but there's information already up about almost everything in the FAQ and anything you don't see everyone will at least put in their 2 cents on...............     mmmmmm breakfast beer!!!!!!

although this is rather hard to admit, I have been reading the site for a while and now I figured out that I really didn't change the oil.  All I did was just pull the plug on the oil pressure port and had a liitle oil come out of that.  And like an idiot I just dumped more oil in...  So for a while now i have been running with way too much oil in it, which would explain the weak iginintion, and the constant amount of oil leaking out the side of it.  So I plan to change the oil and filter, the right way now and fill it with the proper amount of oil.  Then I plan on rebuilding the carbs for general maintaince.  Is there anything else I should do to help the engine after I have really overfilled it with oil like I did?

I guess this just goes to show me that just because I can tear down and rebuild my truck engine and other small engines, that I shouldn't always assume I know what i'm doing.  I should have really figured out what the procedure for changing the oil was first, then do it myself.  Hell I even thought the igition cover was the cover for the oil filter...  Ignorance sucks!

Just make sure you put the right amount of oil in this time I think its 2.7 quarts without a filter change and 2.9 with.   When rebuilding the carbs watch out for all the little parts, specifically the small o-rings under the vacuum cap attached to the slide cap, don't clean your slides or floats with anything harsh either.  Like nolan said run a heavier oil for now in case you have developed a leak.