So I have a new OS 55 AX for my Revolver. I followed the manual and opened the needle-valve 2.5 turns to start with. So the engine idles nice...if I slowly open the throttle, I have it so it will run decently up until 3/4 throttle for an extended period but go further than that and it'll quit. I thought it was too lean....but no matter what I try I can't get it to run at full throttle. I should mention that I'm running a Bisson Pitts Muffler. I'm assuming I need to enrich the idle mixture with the mixture control valve? I haven't touched that yet... Thanks!