I have seen many people wanting YS Engines but requesting NO AC's. What is the reason for this. I am a new YS owner of a NC. THANKS< WOODIE

AC's could be a headache due to cracks/leaks in the airbox which causes all kinds of issues. I wouldn't want one either.

What is YS doing for the people with this known design problem?

I am the current proud owner of a 91-AC in a World Models P-51. I am also the owner of a 91-FZ.


Have they issued any free updates or modifications that can be done to these engines that will improve their reliability?

I thought you were talking about 120's. 91's were seldom a problem unless the engine was crashed.