engine thrust - G-23
 

I'm new when it comes to gas engines. I have a Zenoah G-23 on my 1/4 scale Sig extra 300xs. I watched the identical set-up at an air show and it flew great. Mine is diving to the left as soon as it gets off the ground and I have to keep using right aileron to straighten it out. It's a real bear to try to fly. I'm lucky I havent crashed it yet. I have re-checked the side to side ballance and it's perfect. I have the back plate of the engine mounted to the firewall with a piece of 1/8 " thick rubber between for vibration. Is this engine thrust doing this? Should I add some washers behind the left side of the motor mount? I'm afraid to take it up again without figuring something out. Thanks for the help!

engine thrust - G-23
 

Does it still turn left when you throttle back? If so you may have a warped wing. If not add washers to the left side about 1/8 in. at a time till it straightens out.

engine thrust - G-23
 

I have that same plane with an FPE 2.4. I'm sure you know from reading the manual that the fire wall is at zero degrees. I agree with Flypaper except for the 1/8(.125) I think thats alot. My 2.4 has a center to center hole pattern of 3 inches across the top, I'm going to put in 1 1/2 degrees of right thrust. That's .078 thick washer, a little more than half of that 1/8. But even at zero thrust my plane is'nt doing what yours is.