Thanks for the quick reply!
I thought spark because the backfire through the intake + black exhaust + fouled plugs. It's getting fuel so it must be spark was my assumption since it takes fuel, air, and spark.
The bike is 100% back together with the air filter in and air box on and together as I thought running without that on may have been contributing, but after putting it all back together it was the same.
It has gas and it's not old gas as I refilled the tank prior to parking it to rotate the engine. I did have this issue years ago though when I thought my KZ440 bobber wouldn't run when it turned out to be empty - took a month to figure that out actually so you're definitely right to question it!
I'm going to look back through the tutorial and go back over the bike and make sure it's all together step-by-step to retrace my path. I've unplugged/re-plugged O2, ignition, coil, IAT, and TPS several times so they should be good and I don't have a CEL either so not sure it's a sensor.
Also - if I subtract my DMM resistance against itself from my reading on the primary coil then the coil tests out within spec as well so it (per the multimeter) is good.
Aside from trying to get it to run and spraying brake cleaner around the intake seals - is there any other way to check? I thought intake seal leaks caused lean conditions?
What hoses should I check? I can't think of any hose other than PVC, tank breather, and the hose that zip ties to the rear shock? Just trying to think...
