Crankcase oil in airbox

Hey everyone.
Just got my 81 KZ550 out on the road for the first time since I bought it. It ran great all day yesterday but when I tried to start it today it took a while to warm up. It would stall every time I tried to get it moving from a stop. The first thing I looked at was the spark plugs. They were a sooty color but they were dry. Then I pulled the air filter out of the bike and noticed there was a small puddle of oil on the bottom of the air box. I didn't think much of it and wiped it out. I got it back on the road and noticed it was running better but it was beginning to smell like burning oil and smoke. I pulled over and saw smoke coming from the crankcase. I lifted it up on its center stand and saw a lot more liquid in the oil hole than there was yesterday. The oil also looks to be a paler color than it was when I put it in. Im not sure if oil expands and takes up more room when the bike is running or what but there's definitely a problem somewhere. Any ideas as to what it could be?
Thanks

A couple of thoughts....

1st thought --- How do you check the oil level when adding oil - engine off, let the bike sit for a good while for oil to settle into crankcase, bike on center stand on level ground, oil between marks on site glass? If not, maybe too much oil has been added. This will cause the problem you describe. Check the oil level to ensure it is at the correct height.

2nd thought --- Is it possible your float valves are leaking and allowing fuel to overflow the carb bowls and go into the cylinders? If so, the fuel will end up in the crankcase. This could raise the oil level and cause the problem you describe. Sniff the oil to see if it smells like gasoline, if so, you may have this problem. Ed

Thanks Ed. The oil was added with the engine cols and the bike on its center stand. It's possible the carbs are overflowing into they cylinders. I do have a problem with fuel slowly dripping out of the overflow tubes on the carbs. Not sure how to fix it. Could this be a float height problem? I did the clear tube test the fuel in the tube was about a quarter of an inch above the float bowl.

If the fuel level was above where the carb bowl attaches to the carb body it is way too high. Here some info on carb overflow - notice especially the 3rd item.

Fuel coming out of the overflow hose (the little hose on the bottom of the carb) is the common symptom of the 3 possible problems described below. Remember - NO SMOKING or other activities that could ignite the fuel while working on carbs!

The float valve is not sealing. This may be (and probably is) just a matter of some minor dirt in the float valve and is very simple to remedy and can be done with the carbs still on the bike. Turn off fuel; drain carb by loosening big brass screw near bottom; and remove the 4 little screws on the bottom of the carb bowl. This will enable you to remove the carb bowl. You will then see the float. If you carefully remove the float you will see a stubby little needle that mates with a brass orifice; together, these two pieces are the float valve. Assuming there is no obvious damage to the needle or seat, use a Q-tip and some carb cleaner to clean the seat of the orifice and the needle. Be careful not to bend the tang that is attached to the float. This tang is the piece that the bottom of the float valve needle rests upon, and it determines the fuel level in the bowl, so bending it will change the fuel level. With the float valve cleaned it should no longer leak. To prevent a re-occurrence a quality inline fuel filter should be installed between the fuel tank and carbs. If there was damage the needle and seat should be replaced as a set; they are available.

The brass overflow tube inside the carb bowl is damaged. When you remove the carb bowl you will see a brass tube attached inside and rising toward the top of the bowl. This is the overflow tube and it leads directly to the overflow nipple on the bottom of the carb. Normally, the fuel level within the bowl rises somewhat close to the top of this tube. If the tube becomes cracked or separates from the bottom of the carb bowl fuel will flow through it and out through the overflow hose. Checking the condition of the tube is very easy after you have removed the carb bowl from the carb. Simply hold the bowl level and fill it up near the top of the tube with water of alcohol and see if it leaks. A slight crack in the brass overflow tube can be difficult to find. You can connect a rubber tube to the overflow nipple, fill the bowl with water, put finger over the open end of the brass overflow tube and blow in the rubber end and look for bubbles. If it does the best remedy is to replace it although some folks have found creative ways to repair them.

The fuel level is set too high. This condition occurs when someone has bent the float tang as mentioned above. This condition can be checked using what is referred to as the "clear tube test." The test involves attaching one end of a clear piece of flexible tubing to the carb drain hole and holding the other end of the tube above the bowl/carb joint. When the fuel is turned on it should rise in the tube to a level 2.5 - 4.5 mm below the bowl/carb joint. If the fuel rises higher than that level it may run into the cylinders or over the upper end of the brass overflow inside the carb bowl (mentioned above) in which case it will run out the overflow hose. This condition is corrected by removing the float and gently bending the tang to raise the float valve needle position. Doing this may take several tries before achieving the desired fuel level.

Correcting each of these three conditions involves removing the carb bowl. This task can be made easier if a short screwdriver bit is used, and depending on which carb you are fixing a mirror may help you locate the screws on the bottom of the carb bowl. Also, it is not a bad idea to have a new carb bowl gasket available in case the old gasket is damaged while removing the carb bowl. Ed

I'll pull the carbs off tomorrow and reset the float heights. When I change the contaminated oil is it best to run the bike and warm it up to get the most I can out or will it be bad for the engine to run with gas in the crankcase?

Change the oil without warming up the bike. If the bike has been sitting overnight or for a few days nearly all the oil will have migrated down to the oil pan so when you drain it you'll get most of it out. If you warm the bike you will have oil up top, in the journals, etc. that won't drain out. Be sure to change the filter at the same time.

Be sure to verify you have corrected the fuel overflow problem before replacing the oil, otherwise the new oil will become contaminated. Ed