Hi Full Rudder,
I'm going to recommend that you sell the YS and replace it with a nice user-friendly OS .75AX or similar engine.
YS engines are powerful, durable, reliable. However, they can be a PITA for the inexperienced operator. The fuel system is pressurized to about 6 psi. Great for tank placement flexibility and fuel delivery. Lousy if you have ANY minor leaks in the system and many commercial fuel tanks will blow up like a ballon if not reinforced. They tend to require more break-in before they will run reliably through the rpm range (they are not 'out-of-the-box' OS mount it and fly it engines). The brass pressure regulator, which MAY require minor initial adjustment and then should be left untouched, is a screw driver magnet for many. Just a few reasons to consider selling.

-Will B.