RE: Setting up an OS 1.60, cline, bisson pitts, 18x6w
Are you posative the midrange is rich and not lean? I had a Cline on my 160FX back in 2000 and never had the problem you are experiencing. I removed the regulator as it was not needed. I use them on multi cylinder four strokes in lu of on board glow.
Have you performed the pinch test at 3000-5000 rpm?