The hard starting suggests that your LS needle is too lean. If you haven't yet, I would be tempted to start your tuning process over again, right from the start, where the Low and High speed needles are set at 1.5 - 1.75 turns or so? While tuning, instead of trying to get it as lean as possible, suggest you go the other way. Keep it as rich as possible while still running cleanly (rich engines seldom quit).

Assuming it has one, have you tried running it without a cowl?

Best of luck...