New here looking for help. Stumped on this and can't get any answers to help fix it. I have a 1998 sport 400L with a motor off my old 1996 sport 400L. Rebuilt motor top to bottom and put it on the new frame. When the motor was on the 96 none of my electrical worked head/tail lights dash lights fan electric start nothing and never had a battery on it. Did the overhaul and put motor on frame and got everything hooked up and running. Didn't run long had to do some tweaking and rebuilt carb as well. I didn't have a battery on it. Started it and rode it a little and pulled it back up to the garage and let it idle for a few. Got up to temperature fan kicked on and all the sudden the quad started running like crap. Kind of sputtering and missing. When I try to give it throttle it just falls on its face and bogs. Talked to a guy on another forum and he said it definitely needs a battery to be able to run everything on the quad and function right. So I went out and bought a new battery and put it on. Started the quad and instantly doing what it did when the fan came on. Don't understand this. Sputters and misses when the fan comes on and sputters and misses when the fan is off but a battery is hooked up? Did some tests and checked stator and it tests out good. Was told to check the rectifier next. Tried to check it but don't think I was doing it right. Showed nothing on the multimeter. Any thoughts or opinions would be appreciated on why it's doing this and/or how to properly check the rectifier.