So, I've adjusted the valves at 25,000 and had major problems getting the o rings inserted correctly at the bottom of the spark tube. Keep getting an oil leak that is fairly major. I finally think I have that problem worked out, but now I am seeing a lot of oil in the air cleaner. I cleaned it out a couple of days ago when I first had issues with the front cylinder o ring, and just last night had to clean it out again, as I keep getting oil drops coming from somewhere. My question is, is it possible for oil to make it into the air chamber if the 0-ring around the spark cylinder is leaking? I am getting frustrated with the oil leak as it should have been an easy job, that has me second guessing whether it was worth doing the valve check. I should also add that I changed two shims in the rear cylinder down one size to make them looser, and one in intake shim in the front cylinder. If I made these too loose, would that allow oil to seep past the valve guides into the air cleaner. And if that were the case, wouldn't I also expect to see the engine burning some oil?