With all due respect, I have to disagree with Dar as well. Sure, commercially available RC gas engines are growing in numbers. That's great! It simply means the demand for gassers is growing, and that includes conversion engines. The RC gas engines marketplace is big enough for all sorts.

Not all converion engines use magneto. Some of us prefer to use electronic ignition. In fact, for many conversion engines, it is actually easier to go EI because there are commercially available EI conversion kits so there is little or no machining required.

The Poulan 46cc is a great example of such a conversion. Conversted to CH Ignition, the engine weighs less than 3lbs and will swing a 20x10 or 22x8 with ease. If you can keep the 80" CAP to less than 15lbs, the Poulan 46 will fly it very well.

The Ryobi 31cc is probably the grandaddy of conversion engines, arguably the one that started the conversion craze. Very easy to convert. The old style single ring version wasn't very powerful, but the later dual-ring is pretty strong. Still, it is not enough juice for your CAP.