Why did oil blow out over flow tube? - 2000 Buell X1 lightning

Make sure it has the right amount of oil in the crank case, if over filled the oil will foam and flow out any place it can, Worn piston rings can cause blowby into the crank case , causing oil to escape from the dipstick tube.

Sounds like the air box drain. This is normally to allow any water that might enter the box to drain. Usually when oil flows from this tube it is from overfilling the engine with oil and it is blowing back into the airbox through the crankcase breather tube. This can also happen in the case of carb problems that allow the engine to be flooded with gas thus overfilling it. In this case what you see will be very thin and smell of gasoline.

there is a breather hole somewhere you need to clean it up so you can find it probly on the cap

Sounds like the Needle valve in the carburetor is stuck 'down' letting gas continually run from gas tank into carb. When the valve can't go up (Close) gas will run past the carburetor and into the crank case I bet your oil is full of gas. Check oil level see if it is overfull

see if the oil smells like gas the needle valve in the carb doesn't seat the carb over flows into the crank case washing down the oil

Without seeing the bike, I would guess that this is the crankcase vent. Originally, the crankcase vent tube came up from behind the oil pump and went to the backside of the air filter. A lot of owners changed the routing of this hose due to oil being blown into the air filter. They simply remove the metal part of the tube and replaced it with a short open ended hose running back and ending just forward of the rear tire.

As for the oil blowing out of the tube, it depends on how much oil blows out of the tube. If it's just a mist that will sometimes coalese into a droplet, this is about normal. But, if it's a steady drip or flowing oil, this is not right.

If the mist is heavy, this could be caused by excessive blowby on the rings creating high crankcase pressures. The use of synthetic oil should not increase the blowby unless the rings are in poor shape, then it will. The use of synthetic oil seems to aggrevate any minor leak turning it into a much larger leak.

If the oil is coming out in a steady stream or pumping the oil out of the engine, you proabably have sheared a key in the scavenge gears of the oil pump and it's not pumping the oil back into the oil tank.

Now there is a vent hose on the oil tank but it should be routed to a fitting on the crankcase that is located just above and slightly behind the top of the oil pump.

Good Luck
Steve

Check your oil level . If it is too high smell the oil to see if it is fouled with gas. If your carb needle sticks the carb may over flow filling the engine. When the engine is too full the breather blows the oil and gas into the air box. Another way to get gas in the oil is if the fuel petcock malfunctions and pours gas into the intake manifold. If the diaphragm of a vacuum petcock gets a hole in it , the engine may flood with gas. The gas flows into motor and past the rings. If you look under the engine in front of the rear wheel you may see a tube with a plug in it. Place a pan under the tube and pull the plug. It is a pollution tube for emptying the crud out of the bottom of the air box. Some Honda's used to fill there engines with gas randomly. If it happened you just changed the oil & air filter, and kept on driving. It just happened for no logical reason. So check your petcock and carbs for problems, change your oil and air filter, and always turn your petcock off when not riding.

sounds like you may have broken rings and it pressurised the sump and blowing the oil up the tube

I had the same problem! I found that the needle valve in the carb was not shutting off the fuel flow when not running. Either replace needle valve or put a shut off valve in the fule line. Should take care of the problem

That is a breather tube, I can't picture the motor off the top of my head but that tube is either connected to the valve cover or if the tube seems to go up over the motor then that tube goes down into the motor. If it's the one thats connected to the valve cover then it's possible there is to much oil in the valve box. If it's the one that seems to go up over the top and in then if your just alittle to much over full you'll get oil out of that tube cause that tube sits alittle above the oil level.If your oil level is right on the line then I would run it for a bit then check the oil level. If the level is still good then you should be ok but keep an eye on it if it continues to blow oil out I would take it in to get looked at futher.