Took air filter out to clean and noticed engine oil? in bottom of air box. This was after running all day. Any body any ideas.. Its not filter oil, defo engine..

But, why has this just suddenly happened? weve had the bike since December. The amount of oil in the bottom is about half a finger nail.

Oil in the air box usually occurs when the bike has been running on its side or upside down. It has happened to me many times. nothing to worry about, just keep an eye on the engine oil level. You can disconnect the breather tube which runs from the overflow tank (under tank) to the air box and run the tube to under the bash plate. Not forgetting to block the hole up in the air box. It is only put in the airbox to conform with european environmental leglislation.

oil is in the airbox, as previously stated due to the bike being upside down. Too many wheelies can also cause this, as early ducati 916's were notorious for it!

A few of the Jap bikes I have had have had a little oil lying in the airbox - by little I mean just a smear of oil. this I have always put down to the breather going straight into the airbox & any oil that comes out of the breather is going to end up lying in the airbox - unless the motor sucks it in with the air via the carburettor. This is done I suppose to minimise polution?

Unless there is a lot of oil I would not be too worried. Personally I would let the breater vent to atmosphere rather that re-circulate through the airbox.

Then again too many wheelies or too much time upside down can do the same thing!

Personally I would let the breater vent to atmosphere rather that re-circulate through the airbox.

The crankcase breather can also suck if no PCV is fitted. The breather venting into the airbox also draws clean air from there if negative pressure is experienced.