GK76a Yellow Spark

[GixxerRC]

My bike has done 4 miles in 10 years. Been off road since jan 2002. And I got it jan 2012. it was running.
Come march I decided to start it up as I wasn't insuring it till April and what do you know it won't start.
Sparks were fine so I did the usual.
New air filter
New spark plugs
Cleaned carbs
Replaced carb O'rings
Fully charged new battery
Fresh fuel

Then it started after a while. Next day it wouldn't start and now my sparks are yellow.... One of them is purple!?
When I test spark plug by earthing the thread against engine I get a nice blue spark jumping from thread to engine and yellow at the spark end??
How do I check coil?
How do I check CDI?
How do I check HT leads?
Etc... :S

Thanks

[GixxerRC]

Coil test:

LH Coil 1/4:
Primary 3.8 ohms
Secondary 35 kohms

RH Coil 2/3:
Primary 3.8 ohms
Secondary 'no reading'
HT lead 11.2 kohms
HT lead 10.8 kohms

Secondary with no leads 'no reading'

I've ordered a new coil.