Just bought a Goldwing last night. Unfortunately it is inoperable, that is when I found this forum, so hopefully, I will be able to figure out what's going on. So far I know that I need a new clutch master cylinder (possibly a new clutch as well), a new stator or try to find out what is draining the battery so quickly. The gentleman I bought it from said that there are grounds that are going bad? Also unless I am missing something I need to figure out what is going on with the rear brake since I couldn't turn it on I couldn't see if the lack of resistance, while the bike was off, should be concerning.
Welcome to the forum. That is a great bike you have and will be greater if you can get it on the road. There are tremendous resources on this site and physically in your home town.
Three issues listed.
Bad clutch master cylinder and/or clutch. Assuming you are pulling on clutch lever and feeling little resistance. This could be solved by bleeding the system or it may also be a bad slave cylinder or even old and soft hydraulic lines. A bad clutch really can't be diagnosed without the engine running and oil circulating thru the transmission. For now, get it in neutral, change oil and filter and get it started.
Dead battery. Bad stator does not a dead battery make. While it's possible the stator has a short, I don't think it's draining the battery just sitting in the garage. It charges the battery when the engine is running. If the engine is running and voltage at battery is low, there are several other things to check and solutions available as Terry has stated. If stator is in fact defective you can also do a poor boy alternator install. But first you need to get the engine running to easily determine if the charging system works. You can get a new battery at Walmart or for now just connect the cables to a car battery sitting on a milk crate.
Rear brake. Not sure what you mean by "couldn't turn it on I couldn't see if the lack of resistance, while the bike was off" Not power assisted brakes so they work or don't with engine off. Similar to clutch, could be a bleeding issue, hose issue or master cylinder or brake caliper rebuild, Note brake pedal also operates left front brake caliper.