Wildbil... I'd not choose a weed eater conversion for the USL 120. This plane was lightened by 2.5 lbs from an earlier release because the heavier version did not fly great. The lighter version is a hoot as long as it is not weighted excessively. Weedy conversions simply don't have the power to weight ratio that this plane needs. Do yourself a favor and go with a 20-30 cc gasser weighing 42 oz or lighter. The G-20 ei is excellent as well the MLD-28, DLE-30, Syssa 30, or Aero 28 all would be good choices.