You call the engine a "YS 61S" ...Could you post a picture of your engine?? "YS 61S" is not technically a "real" name and it could easily be confused between two very different engines...

There is a YS 61ST2 which is a helicopter engine and not really "designed" for aircraft use...(I've heard of folks using them on aircraft but they are apparently low on power)...

Or there is the YS 61FS which is designed as a Pattern Aircraft engine...(YS0080)...A wonderful engine as the others have stated...I have several of the Rear Exhaust versions..

Here are a couple of photos...The Left is the ST-2 Helicopter version....The photo on the Right is the FS which is the Pattern engine...