I find it difficult to tune these engines because:
1)My tach (which I know is working based upon the "point it at a indoor light" test) jumps around so I end up averaging it;
2)The tach readings seem different from the front (i know-never measure from the front) vs. the back of the engine or if I aim it at the tips or prop hub;
3)Lastly, I refuse to turn the needles while the engine is running. This really makes the procedure difficult, but I can only imagine how hard it would be to do my job if I lost a finger while tinkering my model airplane. I am trying to figure out a safe way to tune the engine while it is running.