It’s not all it’s barked up to be this ATV thing! Looks like your well into it, how’s it going ?

16.5 volts is too high, that would be the regulator going bad. A quick test is when its not running right to turn on all your headlights, if it runs better, it is voltage related. Should not run more then 14.5 volts , service manual can be found here: https://www.mymowerparts.com/pdf/Arctic-Cat-ATV-Repair-and-Service-Manuals/Arctic-Cat-2003-ATV-Service-Manual/ Schematics are here: https://www.mymowerparts.com/pdf/Arctic-Cat-ATV-Repair-and-Service-Manuals/arctic_cat_2000_thru_2009_atv_and_snowmobileSnow_Wiring_Diagrams__NOTE_LARGE_FILE_459mb.pdf A good online place to order parts is here: https://www.countrycat.com// Mike

Irregular voltage can sometimes cause havoc on the cdi so it could be. As long as your sure the carburetor is properly cleaned and the fuel line going from the tank to the carb is good then I would focus on that voltage right now. That’s pretty high for a voltage reading. Should be no more then 14.5 so I would guess it’s the regulator but I would do a little testing before you buy or order anything. That stator can be purchased a lot cheaper elsewhere also. Download the manual and get a tester, start doing some of the standard tests on the regulator and stator and go from there. If you need any help with that testing let us know.