Hey all, First post to TT, I bought my bike about 5 months ago and it had a new Weisco top end and it ran fantastic. After about 15 hours or so it lost compression and power rapidly one day at the track. After tear down, I discovered the top ring broke at the exhaust port. I ended up purchasing a new cylinder and top end because I didn't want to wait for it to be replated. I just recently rebuild my 2005 YZ250 and it has about 4 hours on a new "B" OEM cylinder and new "B" OEM piston kit. I took the exhaust off last night to look at the piston and cylinder a little just to check things out and right below the top ring is the only wear visible. It looks almost chrome. Is this a common spot for wear. I'm concerned because of my prior engine issues. Could there be a problem with the power valve? The picture supplied is looking up at the piston from the exhaust port. Any advice or experience? Or am I over thinking things?