Ok I was not sure what to search so maybe someone can help or put me in right direction.

Earth cable 

Thanks Tussock,

So...
You press the start button
which energises the starter relay (click sound from behind a side panel)
which feeds the starter solinoid
which completes the battery to Starter connection (click sound from behind the rear cylinder where the starter motor is)
And the starter engages

 This is a basic diagram of the start circuit ONLY, (this is for later models , others may be different, but will give you an idea).. ....

Two things happen when you turn ignition ON ... Power goes to one side of stop/ run switch ,,,, And, to post 30 of relay switch, (not the coil)...See red lines ....
You then press run/stop, (Kill) switch to Run ,, fuel pump primes,,(we are not looking at that circuit) ..... Power then goes from Stop/run switch, to one side of Start Button, (waiting to be pressed), , (yellow line)....

You then  press Start Button, (switch) ,, which sends power to start relay coil , (brown line)...  coil then energizers/ closes, (clicks),,, which in turn makes the circuit between post 30 of relay, (red wire), and Starter Motor Trigger wire to starter motor solenoid , (Green wire),,,

With power  on the Trigger wire, (green wire) ,, (everything being good with battery and connections),, starter motor solenoid will energize/close,, and makes circuit for main power from battery, to start/spin the starter motor ..... Engine should crank / start ,,,, take your finger off the Start Button !!!!!!!

Taking your  finger off the Start Button removes power, (from brown wire), to Start Relay Coil , (ie,,removes power from Trigger wire, (Green wire), which in turn, removes power, (opens), starter motor solenoid,, which in turn shuts down starter motor ......

Hope this is of interest to help get familiar with the starting system and troubleshooting...

Thanks all,