I owned a Fantic Section '95 from new and the Carb. was a mess from the start. Very inconsistent regardless of jetting changes. I finally gave up and installed a Carb. from a mid '90s GG which I believe was a couple of MM smaller. Had to install a manifold spacer on the inlet side. This carb. was available to me as a friend installed a Kehin on his GG and no longer needed it. The only problem was that the idle and mixture adjustments were on the opposite side which required a very long screw driver to make adjustments.
I never had a problem after that even while riding in higher elevations. I ended up selling most of the parts on ebay last year and the carb. is gone, so I am unable to supply any # advice.