Hello again! I've pulled the head off my xr600 and discovered that it will need bored over. Just a couple of questions. My main area of reasoning to bore it out is that there is a spot that is rough in the cylinder. It feels like sandblasted aluminum feels to the touch. I'm just wondering what would cause that so that I can make sure it won't be a reoccurring issue. Also, I'm wondering what the "MK2" on the top of the piston means? There is no other markings aside from the "IN" for intake. I'm guessing its standard bore. Everything else looks sparkling clean on the engine. Really there isn't even any slack in the piston. I've grown up working on motorcycle engine rebuilds.. So I shouldn't need any long drawn out topics on a rebuild of the engine (I hope). Lol. Anyways, thanks in advance for any input!