I just purchased a used 90" Cub J3, perhaps 7 years old. It is a Great Planes kit build. I believe it is a 4.45:1 size. No manual or other documents to go by. Can anyone let me know the settings for the flight surfaces. It has a YS F91 engine in it. What is the prop nut size. this is my first YS engine. Thanks for any info.........DonU

If it is a Great Planes kit, you can get all the information on the Great Planes web site or on Tower Hobbies by bringing the kit and they are listed in the tech notes. Good Luck, Dave

Prop Shaft size is 8mmx1.0

Ditto the info for the plane on the website.