Welcome to the site!
The K4 Colours were Grand Candy Blue(the best
), yellow and Black...No silver I'm afraid
Silver, copper and the GC Blue were the colours on the K3.
I'm not too sure what the K5 colours were but I'm sure someone will be along shortly to fil you in. Have a look around at Sturdeys MC on the A227...
They would be your local dealer
HTH.