Lee:
Like you I have never owned one. The people in Dallas have had quite a bit of experience with Saito's and offer a pricey venturi set up said to be the cat's meow. For a look go to Ultra Hobbies:

http://www.egpworld.com/ultrahobby/catalog/CLACCESSORIES.htm
Windy and Bob Zambelli also have a great deal of knowledge on them.
Seems they are not the rage among the top 20 as they were a couple of years ago.
My observations are that for every guy merrily 4 stroking along, there are 3 more guys in the pits trying to work out the bugs with their 4 strokers.
They seem to be real bad about shucking props.
They are heavy, pricey compared to a similar 2 stroke, and with the pushrods and all hanging out ,a crash into a hard surface is almost certain engine damage. Conversely, a two stroke with spinner into the asphalt has at least a 50% chance of surviving(depending on a lot of things of course)
Opinions, like other things, are something that everyone has. If you think it would be fun, get some good advice and go for it.
Jim

Hi Leester

Many people sing them are  using the  motor as is with the carb set open to differnt degrees.
Other  replace the carb with a venturi and  NVA. the later seems to be a better setup for C\L
There are quite a few  Using MAGNUMS  and  Thunder Tigers, however the class of these  motors  are  the OS  and  Saito engines.

Regards
Randy

Four strokes are a different breed of animal.  They will swing bigger props at lower RPM.  The thing I liked was if needle was pushed to far towards the lean side it would quit.  Also found out muffler pressure was not needed.   They will not turn the RPM of a two stroke, but, they do give tremendous milage.   ---DOC Holliday

I looked at the engine a little more yesterday, it's a FA-45. I'll ask again what 2 stroke engine would you replace with this? And what size plane would this be suited for?