I had similar trouble with this engine, mine came off a MacCulloch weedeater, but the "experts" here seemed to think it was a Kioritz 21 or 22 cc. My flywheel has TWO keyslots, so the timing can be adjusted several degrees just be using the other slot. I tried 4 or 5 different carbs, from size 18/64ths, 20 and 24/64ths, same results. I even purposley ran it the other direction (thinking I had it going backwards before) It was much worse. So I am convinced it's not the carb, the compression is decent (I've seen much worse) so I am thinking it's the crankcase pressure. I made a new crankcase gasket, and the material I used was much thicker than the factory gasket, therefore increasing the volume in the crankcase, and lowering the pressure, but would such a small amount make such a difference in it's performance? I have 2 more of these engines, complete, but since I've been working on the Honda, this one is on the back burner. The only drawback is that I bought the prop hub, muffler and mount from wackerengines, and I feel I wasted my money. Anyone want to buy all 3 of these engines for the price of the conversion parts? You may have seen pics before, I spent a lot of time grinding and sandblasting the "good" one, the other two are still untouched, one with ball bearings, two with roller.