What was trying to be finessed out in this post was really, "Has anybody had any problems with fouling plugs and/or driveability issues after putting on an aftermarket head?" Not so much about clutching.
Some issues have come to light in the last month or so with some issues that are being amplified by a higher than stock compression head. Usually the higher mileage sleds in excess of 1000 miles (like that is high mileage) are the ones with issues. Two sleds with exact same issues and more 1000 miles on them. One's been tore down and problem found, the second one is going to be tore down this week. If it's the exact same cause, I will post the results. If not, then I will keep my mouth shut since their isn't a pattern forming.
So nobody gets confused here, the problem has nothing to do with the head.