Try to look up the model of your engine and figure out your CC or Cubic Inch, you’ll need it to figure in your CFMs. There’s lots of small engine gasifiers built here on the forum, about as many raw wood as there are charcoal fueled ones. Just check out the Small Engines category and browse there for ideas.
Does it absolutely have to be Raw Wood? Charcoal would be more lightweight of a system. Check out the
Air Carbon Fuel Cell thread for an example of a good charcoal gasifier. Runs a lawn tractor.
Or Don’s charcoal lawn tractor here
Nothing wrong with a raw wood system. I’ve made a raw wood gasifier for small engines, I haven’t finished the rest of it though.