Step 20: Mount the Engine
I installed the engine two degrees to the right to counter the engine torque. Simply add a few washers to the left side between the firewall and the engines back plate.
Bolt the motor and wing on and using the center of the wing spar as the balance point.
Mine was tale heavy so I used longer and longer bolts to hold the motor and a wood spacer between it and the firewall.
You will have to play with this to get it right, also you may want to mount your radio battery in the nose for more weight there without moving the engine as far. I used four 10/32 x 3" bolts with nylon lock nuts to hold the motor in place.
Shown below is the 18cc engine, the 25cc engine weighs more so it didn't need to go out as far.
After the engine is mounted and the airframe balances drill two 1/4" holes in the fire wall on the side of the carb. One hole is for fuel in and the other is for overflow and returns to the tank.
Then mount the throttle servo behind the engine like in the second pic.