I pulled my cylinder several days ago. While looking for the c-ring (that fits onto the camshaft >> still haven't found it! ) last night, I noticed the blue scorching on my crankshaft! What is up w/ dat? My last ride I was sucking air REAL BAD via my fuel screw opening. The OEM spring disappeared. I used an ink pen spring to pre-load the o-ring on the fuel screw. Needless to say, the spring was too weak and I had a severe vacuum leak into my engine. I have NEVER seen a crank w/ blue heat marks on it!