If you're having to back the adjusters out more than one turn or so, either someone has made a major error with a previous adjustment, or the position of the crankshaft, piston, and camshaft isn't right. Try rechecking the rocker arms on the companion cylinder to be sure things are set up right. Once again, after a few hundred repetitions, it gets easy to do. The fact you're willing to try speaks volumes about your determination!
I came across an engine once where someone had installed shorter than standard pushrods, and had to put the lock nuts UNDER the rocker arm so he could turn the adjusting screw down far enough to get the clearance right! Never assume the last guy who was in there knew what he was doing!
Jerry
