hi,
just cleaning the air filter ,and noticed there was oil in the bottom of the box,is this normal?,and what causes this.
thanks

Not unusual there is a vent from the engine under the foam on one side or other (left when sitting on the bike?) of the filter box. If the bike has been on it side while running you may see more but it should only be what you would expect from engine venting not a layer of oil per se.

If you still have it apart put some mesh over the filter air inlet in the front (window screen mesh held on with cable ties is perfect). It will totally eliminate flying things getting into the air box.

Do an "Oil in air box" search. More info!

The vent from the crankcase is directed into the airbox. The vented "air" contains a mix of oil vapour and piston blowby. Some of the vented air is drawn into the engine and some of that oil vapour accumulates at the bottom of the airbox.

On Kawasaki ZR-7, there is an oil drain bottle on the bottom of the airbox, not sure about Suzi

Look for the vent hose from the crankcase to the airbox.

Pick up the new second hand 2009 Suzi next Friday and ride back to Byron from Warragul (100kms East of Melbourne)

gg@bb, ava good day