My guess is your float levels are too high.
Are you sure about the 3mm ?? Remember these carbs's floats adjusts differently than the norm. Also make sure of your carb vent lines ( not kinked )
Go for it !!
I have owned four 640's . I seem to miss the 640 Adventure once sold, then I buy another.
This is a gravel bike....does not like tar road riding !! Then vibration is noticable. Can do 500km on a tank of petrol.
Good fairing/ wind protection. The nice long travel suspension...ahead...
Ek sou ook by die steering head begin.
Mens is geneig om die nut bo te styf te draai. ( as ek hom so styf maak dat daar geen play is as ek die vurke trek en stoot, soos die boek sê. Dan is hy te styf, en is geneig tot tankslap. )
I had a 690 with Rally Raid kit. I dropped the bike tank on a rock, causing the one front tank to crack on the seam.
Googled plastic welders.... guy in Pretoria welded it. It is still sealing perfect after 3 years.
Personally I think the plastic tanks of 2 stroke bikes are the problematic...