Hello,

I Need help as not sure what to do next, I recently purchased a 2008 xt660z. Great looking bike rides superb and lots of toys(was also for sale on this site). I noticed on the ride home that I had slight oil marks on my leg, after some investigation I found that the base gasket is leaking.
So I pulled out the engine and removed the barrel . all nice and clean inside the bore.

BUT evidence of some one using a file on the sealing face of the engine cases. I tried to smooth these out with some 600 grit wet and dry with a flat piece of wood. Looked ok so put it back together and run it up.

Its still leaking!

I am confident I put it back together correctly with the right torque settings, clean gaskets etc. I didn't use any sealant. was this a mistake?
How do I flatten the surfaces so they seal?

Thanks for any advice, This is turning out to be a costly purchase!

Dan