But it's the same across the front two and the same across the rear two. What in the carbs is shared across the front and seperate let shared across the back?
I'll do it all anyway

If it was running ok then not having done as suggested cleaning the carbs the might be worth checking the inside of the tank around the lowest point where the tap bolts in for rust or use a surrogate tank to try starting :which would eliminate dirty fuel or any issues with the tank or tap

davethetrucker wrote:If it was running ok then not having done as suggested cleaning the carbs the might be worth checking the inside of the tank around the lowest point where the tap bolts in for rust or use a surrogate tank to try starting :which would eliminate dirty fuel or any issues with the tank or tap

I've been trying it just with fuel straight into a funnel

Okay vacuum pipe blanked as welll ? Was just a thought have seen a couple of nc30s with rusted tanks allowing small particles of fine crap getting through the gauze filter on the tap into the float bowls .

Yup Vacuum is blanked with a grub screw

Bit of a mare this you've covered the main things carbs clean getting fuel OK choke operating fully and both coils producing spark at plugs noticed in picture some unusual wiring around rear coil is that an earth wire from the subframe for the coil pack rechecked all wire connections rear plug leads right way round I know it's stating the obvious .

davethetrucker wrote:Bit of a mare this you've covered the main things carbs clean getting fuel OK and both coils producing spark at plugs noticed in picture some unusual wiring around rear coil is that an earth wire from the subframe for the coil pack if subframe alloy ?

All earths go to standard rear earth point. Yes its an alloy subframe.

Might be worth doing what you thought of trying overlaying original loom and cdi remove plugs fully charge battery and come back refit plugs and try that after a day away sometimes brings a fresh approach to fault finding .

I had the same symptom once,The only way the bike would run was to bump start it at high speed,
When running it would pop bang and fart,Changed the cdi bingo run like a watch.

yup,does sound electrical to me...cdi...pick ups..or more than likely wiring!!good luck ben!!