I would be checking the spark first, sounds electrical.

So I've checked I have a good strong spark on all 4 cylinders
! But how can I check the spark is in the right cylinder at the right time?

You can not check it.
Makesure the low tension wires are on the correct coil as it sounds like the sort of problem you get when back to front.

Another quick question on the chi unit which of the coil wires are on top? Is it the white one or the black/yellow one?

It's alive :) thanks for all the help guys...

Great news.
What did you do to fix it?

're-checked the timing. Which was out but 1 tooth. Then checked for signal from the cdi to the coils. I found one of them was shorting out so it was always firing.... run a new set of wires for the coils.... and it started..... spent the rest of today rebuilding her and noticed the rev counter wasn't working . So double check the wiring diagram, and the coil wires extend to the rev counter. So I run fresh wires there to.... all fixed now just need to seal the tank an then fill it up....:) just in time fir summer..

Well done mate glad you got it going I wish i was going to be on the road for summer

I’ve got a non runner GK76 and just wondering how I tell which is the right and left side of the coil and? Two ht leads go to one single coil and the other two HT leads go to the same coil but those have both have click on connectors. Any help please