I never try to idle any YS at 2000. I like to be slightly into the regulator at 2200 to 2400. It's personal preference, but it works for me, and a whole lot of other flyers as well.

I think your only problem is the regulator is set too rich for your altitude. Start screwing it in 1/4 turn at a time until it works properly.

The 110 runs fuel through the lower case just like all YS engines other than the DZ's. The DZ's depend on blowby for bottom end lube.