I was taking my RB R3 engine apart to give it some maintenance and check internals after the last time I used on my 720 and There a pretty big scratch on the sleeve and the piston.

What could have caused this?

The engine has about 2 gals thru it, I can feel the piston still fits tight inside the sleeve but what will happen with performance now?

What should I do? piston and sleeve replacement it's expensive I rather just buy a new engine. should I just keep running it? I haven't started it since I put it back together.


Thanks!