Bugga!
I just thought that if there were sets of needles and main jets that made the mixture increasingly rich, there might also be sets that went the other way…
Who knows: You might have ended up with ‘rough’ running, due to differences in the mixtures being delivered to each cylinder through a messy induction system, but then again, you might not have.
Looks like we’ll just have to wait for Jabiru to do what Oracle1 is suggesting they should do (as well as ensure sufficient air flow for cooling in any event).