Is anyone using 4 stroke engines for stunt and CL?  I see Brodak sells the Saitos. 
They seem big and heavy, of course.  But they are easier to obtain.

  Four strokes have been in use for quite a while. Like just about any other power plant, you have guys that love them and guys that wonder why anyone messes with them. They do operate entirely different from two strokes, and make a different kind of power. When they are set up correctly, they make a very interesting and consistent type of power. They run a lot quieter that even two strokes on a pipe. Like Fred suggests, fins the four stroke forum and spend a couple of days reading! Lots of good, useful info there that can greatly flatten out your learning curve. I have a Top Flite Score with a Saito .56 in the nose and it was quite an experience going from the first flights to almost a year and a half of learning to master the type of run I thought I wanted, and finally got there after setting my model and engine up like Bob Reeves of the Tulsa Gluedobbers came up with. I like it a lot, but haven't sold off my other engines just yet!  4 strokes are all about fuel draw, hot plugs and getting propped correctly to match the speed you want to run your engines at. Paul Walker won the NATS one year with a nice Mustang with a Saito in the nose I believe.
  Good luck and have fun,
   Dan McEntee