i have went and sanded everything-somethings had rust on them-bike is missing terribbly-when i did the topend a couple of months ago the crank barings were fine and i checked them again by teying to move the flywheel-a plug won't work in the bike-it is a 1998 yz250-i will take it out and put it in my 03 yz125, and it will run fine-is this a weak spark-is my timing off???advice is greatly appreciated