RE: motor sideways or inverted?
Dave,
OS makes a mount that fits the Saito 100 perfectly. People at my hobby shop are all usuing these mounts for their Saito 100's. I have no vibration and the engine is smooth. I did have to adjust the low end because it was running rough between idle and 1/4 throttle. Not a big deal. Once it's set you will never have to touch the low end again. So if you could run it w/o the cowl to see if low end adjustment is needed. I would also change the stock plug to a F plug. I wasn't a Saito fan until I bought the 100. I also used quality tubing but forget which brand it is. I've had two 180's and they vibrate like crazy. I used the stock hinges for the plane. I put the plane through all it's paces and haven't had any problems.