KMOT , just a quick quirck, some one might have mentioned this but, anyway the worst thing you could do is convert over a weedeater/chainsaw motor, reason: A gas weed motor is designed for shaft drive and or centrifugal clutches, by this I mean the bearings on the crank are for longitude support( up and down pull) when you convert a weed motor to a plane motor and fly, the prop is putting a pulling action on the motor, side to side(pulling straight out) this motion is putting pressure on the crank bearings, the crank does not have the proper thrust washers and/or bearings to handle this load, A Desert Aircraft 50 (for simplicity) has sealed crank bearings that have a longitudle(I.E spelling) support. HHHHHHHHH anyway by converting the motors it will run semi good but will wear out much quicker not to mention using a magneto type ignition, thats why a $80 simple weed motor with a $30conversion and no warranty = $110, and a Desert Aircraft 50 $549 (has electronic ignition, machined case, proper bearings, excellent warranty service, and great looks) + muffler $59 = about $607 dollars. Sorry KMOT if I was long winded but I hope it makes sense.