Quenton, that info was great! I found a couple problems that I've corrected.
This NE5 has your machined head on it (used to be Lennyharp's bike), so it is set up for the shorter plug. I pulled the plug out and found that the insulator was cracked and dangling against the electrode. I think that was my fault when I regapped the plug. At least I found it. I found an NGK at the autoparts store that cross referenced with it, so that went back in the bike.
Next up, I was looking around at the connections at the coil. Found the female spade plugs on the wires at the coil were VERY loose on the coil spade terminals. So, I pulled those off and slightly crimped them with pliers so that they fit snugly.
Next up, when I pulled the replacement plug, I found that the plug was soaked with fuel. So, I pulled the carb out and I think I just may have found the source of the main problem.. I pulled apart the float bowl and found that the soldered brass floats were half full of fuel. This flooded the bowl and thus flooded the engine.
So, I guess i get to build the custom manifold and install the new dellorto carb sooner than I had thought.
So, Quenton, what length intake runner would you recommend for this engine? I am thinking a 3-4" runner from the port on the head to the carb would give me a bit more low end torque. (at least thats how it works on 4 stroke automobiles)
The carb is a 24mm Dellorto PHBL. Intake runner material is 25mm ID. The manifold to head port flange will be portmatched to transition as smooth as possible. I could also use the aluminum intake block as a smoother and longer transition between the 25mm intake and the smaller head port.