How much time have you got on that 2.10?
Mine has about a gallon through it and turns an APC 16x14 at around 8200-8300 peaked (briefly ) but I richen it substantially for flight. I'm using a std. Bisson Pitts muffler...not the Sundowner specific one and 5% Omega.


Spit...the 1.20 will probably fly it, but not very well IMO...or not in the manner to which it's designed anyway.

You'd probably also need to move things forward to get the C.G. correct...make sure you have the 2 alum. tubes in the stab...not the solid steel rods?