Is it time for plating!?
 

Hi all,

Recently bought a 2010 ec250 six days and having taken the head off to check piston (around 80 hours green laning im told) i discovered one line of scoring above the exhaust port. I can feel it with my nail. The piston is not worn in that area as such, there is just general blow by on the rings from an old piston. Can i get away with a new top end kit or should this be plated? The rest of the cylinder still has the factory crosshatching on it!

Thanks
Mike

Is it aluminum on the surface of the plating or is it a scratch into the surface?

Try a little muriatic acid on it to see if it will remove it. I would consider a replate if it doesn't come clean, but as my old boss always said, "we've won world championships on worse than that!"

It does clean up a bjt but thats mostly scoring i think. Attached another picture which i think shows it better. Im wondering if i can get away without making it worse until next top end time...

If the previous owner ran it like this, I guess you could also :)
But to me, it seems like a damage that has to be fixed. From the latest picture, it seems like the plating is worn through and you look into the cast aluminium. But images can be difficult to interpret.

As much as i want to sling a new piston in and hope it works so i can get out quicker, i think its wise to send it off for plating so i get a trouble free winter (with any luck!)

Thanks all for your advice.

If it is not a gouge you can also have it diamond honed lightly.

What he said. Certainly looks like the plating has come off/worn through. If I had to get away with it for a race or two I probably would, but it's not going to fix itself.