Big difference between NGK and the correct champion plugs. this is the correct plug for your motor Champion QL77JC4 .
you should never put the ngk plugs as they are not compatible with your motor , no matter what a shop tells you.
No spark can mean a few things, but first do check connections everywhere. !!!!
the spark gap jumping of 7/16ths for the plugs to jump is a good indication if the spark is strong enough.
you can easy make a spark jump tester or buy one for just a few dollars.
give the coil leads a good clean and undo the bolts and take the coils off then put back once cleaned around the bolt area's.
I did also do this with the complete plate that holds the coils and other electric's, only takes a small piece of dirt to stop a good ground connection.
and like said above sometimes these motors will run on just 2 cylinders and out of water will sound like plenty of power.
before replacing a coil swap it over with one of the others to double check its not bad connections .
Also do make sure none of the brown wires or black and white wires coming from the temp switch (top left when looking at cylinder head from the prop)
are not touching any spark plugs wires or coil wires, this can give interference in the signal and send the power pack into frenzy.
I had a few issues with my motor and it all was due to corrosion and broken wires, but it kept on seeming like a fuel problem.
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this forum will definitely get you in the right place, loads of people are willing to help out because most of us also got some good tips and tricks from this very place.