K Model heads crack. Most heads I see are cracked. A common place for cracks is up the spark plug threads, then across the flat surface of the head, going away from the spark plug. I noticed a crack near my rear spark plug. Wiley suggested a wide, large OD copper washer under the spark plug, covering the crack. I found a washer at Car Quest. Cleaned the crack with some electrical cleaner, a bit of sealer on the crack. Removed my current spark plug sealing washer, and replaced it with the copper washer . . . tightened it all down - and now I have full compression again (7:1) in the rear cylinder, and no leak. I can now keep riding in this great November weather we are having. Sunny and 65 ! Then Sunny and 55 . . . then Sunny and 45 . . . then cloudy and 35 . . . then cloudy and 25, then 15, then 5, then -5 . . . then "this sucks . . ."