I was told to do my crank when I do my third piston, so it's time. Is that a reasonable time frame? I have no hour meter, but I am guessing the minimum hours is 80 plus. Could be higher, dunno. If it's time, what bearings do I need to replace in the bottom end, besides the mains. I was looking at the oem parts diagrams and stuff adds up quickly. I'd like to be cheap but not foolish. Bike is a 2007. I don't race, but I like hitting the tracks. thanks.