Hello,
I have a 2001 Artic Cat 250 2x4. It started running very rough above an idle the other day, intermittingly. Now the problem is all the time. I cleaned the carb. and replaced the spark plug, still the same problem. A friend told me to check the timing. I don’t have the tools so I was cleaning the connectors for the CDI and voltage regulator when I noticed the battery was bubbling when the ATV was running. I checked the voltage and it was 17.9v at idle. So I turned on the headlights and it dropped to about 16.5v. I took the ATV out and it ran fine, but as soon as I turned off the headlights the engine started running very rough again. I must assume a bad voltage regulator, putting out too much voltage and messing up the CDI, but is there anything else I should check before spending the $$ on a regulator? The problem started off intermittingly and a regulator usually just quits. Thanks for any comments and sorry my post is so long!..Joe

 

The only thing that can cause your problem is the voltage regulator. Nothing else is gonna fix it either.

 

Be sure to check your connections. Bad ground can make your regulator do some goofy things. I to suspect that your regulator will fix the problem but check connections or you could be doing the same thing soon.