I have experienced some "more than usual vibrations" on the DLE 30 during initial tuning and break in on all of my 30's . I balance all of my props so that the will stay in any position you put them in on the balancer . So prop induced vibration on mine didn't seem to be the cause of the engine vibration . Through prop swapping from engine to engine on other DLE 30's , some with much more run time , I was able to pinpoint the vibration to state of tune and break in on each engine. After they all had a few gallons of fuel and some more retuning along the way the vibrations lessened to what I determined as a normal level . The engine with the most run time (probably 10 gallons of fuel ) is now and extremely smooth running and very strong engine . On that engine I have seen tach readings over 8200 RPM with the Redwing 20x 6 prop. A note on the tuning of the DLE 30 or any DLE engine . Be sure to use an NGK CM6 plug gapped around .020 " and set the ignition timing between 28 and 32 BTDC . ALL DLE engines I have checked new out of the box have had the timing set too high ,some as high as 45 BTDC . I feel that the incorrect timing makes the engine more difficult to get through the engine break in and tuning stages. Now I set the timing and discard the DLE spark plug as soon as I open the engine box .