well its a pretty mild temperature here today so maybe i will throw the battery in the bike and run her up, just got to check the impedance of the coils and make sure that they are good.

thanks alot for all the input everyone.

 

Something else you might do is chuck some Seafoam in the gas tank. Might be that it really just isn't completely clean no matter how many times it has been gone through. My experience is that the only way to get a system really clean is to run something in the gas as that gets everywhere. It's a cheap fix if it works.

 

Lean mixture is one cause of NOx which is created by high combustion chamber temperatures. Can also be caused by defective EGR components, carbon buildup, failing cat converter, or high engine coolant temps. The CO and HC measurements are where you want to look to determine rich vs lean.


As for the OP's question although the coils are a possibility it's not a very common problem. Has the engine compression or valve clearance been checked? It does sound like a possible carb adjustment/cleaning problem even though they have been worked on already. I would rule out any engine mechanical issues with the compression & valve clearance inspection first and then move on from there if you don't find the issue.