ORIGINAL: rollmyown

Hi Dave,
Thats interesting what you did. I have worked on a couple of Weedeaters, but I haven't flown one, yet. One point I might question is about the piston ring pin. Did you keep the area of the piston and its ring pin running in the same area of the cylinder that it used originally? The area where it normally runs is wider than the other side. If you lifted the connecting rod from the crank pin and turned the whole assembly, it will all be in the same relationship as built by the factory. Another point I would ask you to consider is using the blower crankshaft the way you have it so far. I have one of these long crankshafts and I don't think I would trust the flatted end of the crankshaft to hold a prop on. I think it would be much better to cut the shaft and thread the end, but it has to be done on a lathe as you probably know, or just find another crankshaft from a Weedeater trimmer. I would be wary of using the long shafts to drive a prop for another reason, the prop is pretty far from the bearings, this amounts to a fairly long cantilever load on the bearings. The airplane when in flight has a spinning gyroscope in the form of a propeller and when you turn the airplane the gyroscopic load is considerable. Remember holding a child's gyroscope toy while it spins? you can feel the load when you move it around and what are they, 3" in diameter. This is long but it it also could be a safety issue. The bearings probably wouldn't last as long either.

I am converting two of the 25cc Toro engines you posted the photos on. I need to find a metric? tap to match the threads on the shaft to machine the prop hubs. The rest of the bolts are SAE! One of these engines has a two barrel carb and the other has a single barrel carb. I want to test run both of these soon. These Toro engines are high compression compared to some others and I wonder how smooth they are going to run after conversion. I ran them before I started to convert them. I suspect one of the reasons they are on the surplus market is: Did you notice how hard they are to crank with the cord? The pull cord system is a relatively small diameter and the compression is high, so they are hard to crank, but the quality of the engines and the machine work is also high. I'll post what the results are later.