I have the jrc carbs on my '72 pretty well dialed in except for 3/4 to wot sputter. Main jet right? Plug chop shows lean if anything and when I go to progressively larger main jets it gets progressively worse. I'm down to my smallest main jet, a 35. And before I send off for smaller ones I figured I'd plumb the depths of our knowledge pool. The only thing I can think of is fuel starvation. Is this a common tuning problem? I'm running 1/4" line no fuel filters. Thanx in advance Rick.