Have a YS-120NC mounted inverted problem. Using two YS-120NCs mounted inverted in a Tiger moth I'm having problems keeping them running when I come off of an installed glow driver setting.

wonder if it is because my tank centerline is 2" above the YS-Inlet? Both engines worked fine in a fusledge center mounted tank and the engine inverted. Ran into a man in NJ that has to keep glow on in his YS inverted all the time.

Any answers or suggestions?

G'day Mate,
It is important to keep the fuel tank centre line level with or 1/4" to 3/8" lower than the needle valve on any motor, upright or inverted, 2 or 4 stroke. Doing this will solve 95% of your engine problems.

The tank position means nothing witth a YS. The fuel system takes care of the fuel delivery problems associated with tank placement. I have never ever seen a Pattern plane with onboard glow. A YS will idle better than any engine out there inverted without onboard glow.

Yep....inverted or upright doesn't matter. Fuel tank placement doesn't matter.
What does matter is that you run the right fuel, the right plug, and the right
prop....then when you get the engine adjusted properly, it will run perfectly.

FBD.

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 .