I would like to put a nice 4 stroke in my Sig Rascal 40. Tower suggests .53 as the largest. What are ya'll using and how much did you have cut away. Pics would be great if you have them. Thanks for the help. Oh ya will I be able to use stock muffler on a Saito 4 stroke. I have never had a stroke - are they a lot to maintain?

rab

I used a os48 same as a 52 and had no problems installing it.
Had to cut out a gap for the header pipe for the muffler and a hole in the side for the needle valve, but I dident have any problems.
change the engine mounting screws to socket head screws.....makes it easier to tighten in the back holes.

I squeezed a Saito 56 in mine

I put a YS 63 in mine. Only had to cut a small opening for the exhaust header as seen in pic. The YS 63 pulls this plane vertical like a rocket! Any four stroke around 50 size will work fine.

Jim

Put a satio 56 in it. You will be glad you did. It's a tight fit but it can be done. You can trim back the lip on the bottom of the engine comparment to make it more accessable.

I currently run an OS .46 FX, but have run an OS .52 in the plane. I prefer the performance of the .46, but the .52 is no slouch.

However, if you can squeeze some more 4 stroke power into the nose, like the Saito .56, I'd suggest it. Heck, I was considering putting in a Saito .91, but that would be extensive modification, and would probably push the plane's operational envelope to where I don't really want it... The point of destruction.