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Has it got points or electronic, points had to be spot on to fire, electronic needs a really good battery
You say new coils are they pattern and if so are they same ohm rating as original, no i dont know from memory what that is
If you fitted new plugs make sure they are not a resistance type (marked with a 'R' after the plug code such as B79 R) because if you have a resistor plug cap as well as a resistor plug the spark will be weak. It has to be one or the other, not both. Are you definitely getting fuel through the carbs?
You could try running a separate live to the positive side of the coils to eliminate the possibility of excessive resistance in the wiring. As standard the Live goes from battery to ignition switch, through the kill switch then to the coils. That involves a lot of places where poor or dirty connections are possible, which can seriously affect the coils performance Sent from my POT-LX1 using Tapatalk
Be worth checking carb slides are all way down and that butterflies can close, i am working with a very old memory here but i think the slides are handed so can be wrong if mixed and a bit like bench sync on the 500 you can have the butterflys too open to get a start.Compression is low but that could be the gauge type and its the same after as before, i do know those carbs are a swine to clean, bit like the 250 N superdream----could take 4 or 5 goes to get clean and sometimes even that didnt work