Motorcycle Repair: Ex250 oil in the airbox, kawasaki 250r, freeway speeds

Question
I own a 2006 Kawasaki 250R Ninja. When riding at freeway speeds oil builds up in the airbox, then it leaks out the left side of box down the kickstand. I have had it at the dealership 4 times. They keep saying that they fixed the problem. But after just about 50-100 miles I have another 1/4 quart back in the airbox. What can be done to fix this problem permanately? Maybe aftermarket k&n fitlers to replace the box? Any help or info would be greatly appreciated.

Answer
Hi Chris.

Whatever is causing this, changing the filter system is NOT the answer.  Check your air filter and your oil level.  It could be due to excess oil or there could be blowby causing a pressure buildup in the crankcase.  Have you checked the valve settings?  If the gap and timing are off, then it could be building pressure in the case by allowing exhaust gasses get past the valves at the wrong time.

How about the air filter?  Is it dirty or clogged?  That could cause a pressure imbalance which is pulling oil from the crankcase to compensate for the reduced pressure through the filter.


Start with that and let me know what you find.
Good luck and ride safe.
FALCON