ORIGINAL: Rcpilet
I think a mag. needs about 300-400RPM to generate a spark.
Pull the plug and lay it against the head. Hook your cordless drill to the crank and spin it with the drill in reverse. You will quickly see how fast you need to spin it to make a spark.
Thats why electronic ignition is so nice. It sparks at any RPM. Makes for very easy starting and a silky smooth idle.
Hmm...
I can pull the cord on my weed wackers (all 3 are ryobi) with a very light pull and see a rather strong spark across the plug with just one rev past TDC.
Hell, I've always seen that on any magneto type engine I've ever checked. Briggs, Homelite, Ryobi, Kohler, Techumse...
It don't take much more than a little pass of the magnets to kick the coil.
I've seen lots of folks stick a screw driver in the wire and hold it by the head. This is ok, but I seem to get better results by taking the plug out of the head, which releaves compression, and put it in the wire. Then you can hold the wire (unless it's cracked, then it will add some spark to your life
) and press the plug threads against the cooling fins of the head. A light pull on the cord, or in this case, flip of the prop and snap... spark!
Tom