1952 Model K

This motorcycle has more miles on it than most baggers runnin' around here.  It's been together for 12 years now, and the head has been cracked for 10 . . . the extra air keeps my mixture a bit cleaner on the rear cylinder, and evens out the jetting.  If I remember correctly, this cylinder has a +.006 tapered spot in it too.  The pistons are +.070 (last hurrah on this one) and I just decided to run it.  It's my own bike, so I have the authority to do that . . .

The plugs always read the same.  A little more oil detonation(that's what I call it) on the rear, but not bad.  The head is cracked so bad, the blow-by oil wicks it's way around the outside of the sparkplug insert, so I run a big, copper washer under the plug to help stop it - and seal the plug.  When the motor gets hot, it kinda seals it up.  I have some different heads, so I'll try those.  You know that K-Models don't use head gaskets - precision engineering !  Try that on your Evo !
(PS. 6.5:1 compression may have something to do with it?)