I think I found the best ignition for my Poulan 25cc. Glow plug. Engien fires and runs smooth on regular gasoline/oil mixture so the glow needs to be powered all the time. I also check the option of using gasoline-methanol mixture maybe to save on on-board battery, and it runs fine, but with glow powered all the time it runs better. Even it starts by hand The performance is a little better (50 rpm more with glow than with magneto). Running on gasoline-methanol mixture (50%-50%) increased performance by additional 300 rpm.

So this is the best weight saving option:
- glow plug (with adapter) weights only 1/2 oz, regular spark plug is 1 oz.
- on board battery needs to deliver only 1.2V (not 4.8 for ignition). It needs to give four times higher current tho, so the battery weight gor glow is the same as for ignition for the same flying time.
- No ignition module needed so this is the saving 2 - 5 oz (depends on the ignition brand).

And the best factor: cost I turned my own glow adapter, but you can buy one for 10 dollars or so. I didn't see ignition available for $10 or less.

My goal is to have this engine 2-1/2 lb or less ready to fly: Engine with prop hub, muffler, mount and on board battery. I couldn't make it with ignition. (it is about 17oz more with magneto).

RysiuM