I have 4 YS engines mounted inverted and all run fine W/O any onboard glow.Its already been said that to a YS tank position is a non issue.

I did have a little trouble with one but it was the regulator setting ,it was to rich for some reason at flush.

Flyboy Dave has the right Idea here .

You might ask Dave Shadel in the YS forum also, he may have some info for you .