How much oil does my bike hold it is a 83 suzuki gs750es.

Low on the right side crankcase cover there is a sight glass. Have someone hold the bike level (not on the side stand) and check the oil level through the sight glass. If you can see oil while the bike is level, you are ok.

There is a small sight glass on the right side down low by the footpeg.

It is difficult to hold the bike upright and check at the same time. Have a friend check while you hold the bike, or use a small inspection mirror to check the level.

either get a bike lift or centre stand or lean the handlebar against a wall, you will find a spot where it is close to verticle.
leave the side stand down so it cant fall on you if it over balances away from the wall

Your manual should show specs for oil with and without changing the filter, if not then put in correct amount minus one pint and check it! Add as needed.

The bike has to be both level and vertical when you check it - not on the stand.
It would be good if someone can hold the bike up for you when you remove the filler plug (which has the oil level dipstick attached) from the cover on right side of engine, Or you may be able to sit on it , holding it upright with your legs and reach down with right hand to remove the filler cap/dipstick.
Wipe off the stick and re-insert it and screw it all way closed, then immediately remove it again. The oil level shoud be between the two indicator marks on the flat tip at the very end.
If bike is on side-stand you will see nothing on the stick - bike must be upright,
If you need to add any oil, use a funnel and put the oil in through the same hole the cap/dipstick goes into. Best use a motorcycle specific oil - automobile oils contain additives that can cause clutch performance issues
Good Luck!

Nice 1st bike you can pick up a shop manual for it and have a lot of fun riding and working on it.

look down low on the right side of the engine, their is a "sight glass" that you will be able to see the oil level, tilt the bike a bit and you can see the oil, leave the bike on the regular kick stand and if you can see the oil in the glass the level is fine, above that is the oil fill cap, that is where you put the oil, i think your bike holds 2500 cm of oil, that is about 2 and 2/3 quarts of oil. remember that motorcycle oil is different than regular car oil, this is a common mistake which also leads to the clutch plates sticking together after a bike sits a while.

http://www.alpha-sports.com/suzuki_parts.htm

give this a go you can get your part numbers from here

the bike takes just a little over 3 quarts of 10 40 and yes check it while its off