Re Mr Schafer's comments on the Enya 5224 as a stunt engine. Well it isn't a RoJett or big megabucks sort of engine , but propped correctly for the model, they are an excellent engine and they don't need much in the way of taming. If you have a choice, use a low compression head or a thick shim. Something like a TT 10.5 x6 prop and you will get an excellent 4-2-4 at somewhat higher revs than a Fox 35 and with a good bit more power. I prefer a slightly rich 2 stroke and it will do this too on something like an 11x4. Don't try racing with them, they are not really built for speed!
They are a very cheap engine second hand and do the job better than a Fox 35 in my opinion, they certainly last longer than a Fox! Read Randy's epistle on fuel and remember they need a lot of oil. I use half and half castor/synthetic at around 28%. A good "old style" engine for stunt.
Andrew.