Trying to figure out what wire I can splice this radio wire (or it's ground) into so it will only come on when the key is on and shut off when the bike is off, suggestions would be appreciated.

 

stick a test light and find one that is hot with key on and not with key off

 

headlight will work, your speedo gauge power line (typically what i use and then run your remote line to that) will work just fine or to your relay set up

 

I soldered it in with the hot lead with the key on, works well thanks guys