I bought a used 2009 KLX 250SF with no owners manual, what type of oil and oil filter does this need? Any recommendations on high performance spark plugs too?

 

https://www.kawasakiforums.com/forum...q-links-30733/

You should find your answers and a lot more in this thread. There's a link to owner's manual. I run NGK iridium plug.

 

I use Motul 5100 10w40, with the oil filter I usually pick up cheap filters on sale. I forget the part numbers at the moment but the same filter is used on many other bikes. They also make a metal oil filter you can reuse.