Interesting, I`m a Machinist buy trade I will give it a try machine the valve seat and shortened if needed thanks for the tip.There are lots of new and reproduction valves on ebay. Just go over a do a search. My head had about 24,000 miles on it and the valves were grooved. The valves and seats cleaned up just fine. The stems needed to be shortened a bit to allow adjustment. It looks like old OEM valves are about $80-90 each. I've put about 2,000 miles on the bike and it runs great.