So I did something dumb. I noticed what appeared to be a small amount of oil on the bottom left side of the carburetors. Could have a valve seal issue? So I looked at the sight glass on the crankcase and I noticed the oil level was below the minimum fill level. So I added oil until it appeared to be at the appropriate level. Hit the starter and heard a glugging sound. I let off the starter before the engine turned over and noticed oil draining on the ground from the breather hose. I looked at the air filter and noticed oil had come up into the air box. The oil did not make it onto the air filter itself. I assume I just added too much oil?
But Im confused as to why the sight glass showed the level so low?
I plan on doing a full oil change tomorrow and cleaning out the air box. Anything I need to inspect before I try to start her back up? Should I be worried about any kind of damages?
This is one of those topics where the information keeps going round and round and when this happens I have to go back to the beginning and figure out what started the topic, where we are and what to do next. So.....
You went to start the bike and go for a ride and "Noticed oil drops on the left side of the bottom of the Carburetors and thought you might have a valve seal problem."
1st question. At this point was the bike on the side stand ? That would explain what you saw on the bottom left side of the carburetors
2nd question- At this point did you put the bike up on the center stand and check the oil level and found the level low? if you did this and didn't allow 5 minutes for the oil level in the crankcase and sight glass to settle down with cold oil, it would explain why you thought the level was low.
Then you report that "you topped up the oil until it shows correct in the sight glass" if you did this then it's possible that you overfilled the crankcase with oil because cold oil takes forever to settle out and show the correct level in the sight glass.
Next you report that you attempted to start the bike and heard a glugging sound at which point you stopped trying the starter. SMART !!
Then you noticed oil coming out of the air box and thought you may have overfilled the crankcase and you decided to change the oil and clean out the air box.
3rd question.- Did you do an oil change or oil and filter change ?
4th question - Was the oil full of gasoline? This is where you might suspect that the crankcase got filled with gasoline and that would explain how the crank case vent "glugged" oil into the air box . in order for this to happen a few things would have had to happen. First- the fuel was left on and you said that you left it on prime so - possible. Second the floats in the carbs didn't shutoff the fuel flow. Possible maybe even likely if the bike was left on the side stand. Third the time factor-For all this to have happened, the carb floats got stuck open, the gas flowed down the intakes and into the cylinders with open intake valves and filled the cylinders with gas and that gas passed by the piston rings and into the crankcase. All this takes time.
5th question - If you did an oil change only, how much oil did you put back in ? if I remember right you have a 1980 KZ1300. Oil capacity of 4.5 liters with a oil filter change (which is 4.75 U.S. quarts). Subtract maybe a 1/3 of a quart if you didn't change the filter.
At this point I would remove the spark plugs and turn the engine over on starter. if the cylinders spit out gasoline, you had a hydraulically locked cylinder (s) and may have bent a connecting rod but that usually only happens when a cylinder is hydraulically locked and the engine actually fires. I don't think it's possible to have the starter by itself create enough energy to overcome a hydraulically locked cylinder and bend a rod.
So pull the plugs and turn the engine over on starter and let us know what you find and we'll take it from there.
KB