Keep in mind that both the DL and the 3MM came out about the same time to contend with other 50cc engines. I have one each of the very early ones. In fact the 3MM I have doesn't even say 3MM on it. I bought it from Adam Vorhees at BCMA and he removed the labeling on the front of the cylinders. The 3MM is a great running engine with a third bearing that makes it run very smooth. The DL has always been lighter and a little more powerful. 3MM is also a side carb engine. I took mine out of the plane to test another new 50cc. If it weren't for that it would still be in there. They run great. Sorry to hear they are having QC issues. Seems to be a habit in China these days.

All,
Yes I have one and work with TF at WH and he is dissapointed with 3MM in that he cannot get them to acknowledge their is a problem. The 106 Tom mentioned (and I flew it in a 540, was peaky, had an on/off feel to the throttle)
and was down on power. (About the same as a BME 102) The DLE 100/111 is a power house, the DLE-55 is also a power house but these light engines cause lots of weight distribution challenges.

JDS