I have a 1998 mxz 440 air cooled. Pulled it out last week and can't get it running right. Put some fresh plugs and gas in it and ran great for day or two. Now it will fire and run for a bit but will eventually stall out and plugs will be wet and black. Are carbs out of adjustment? What should screws be set at? Also brake light not working. Had a kid do some work on it last year and when got it back the seat wasn't on properly and tail light wasn't working. Pulled it off and saw 2 diff plugs comming out from under gas tank but only 1 plug coming out of seat. Now tail light works but not brake light. Help! Trails open wed and I'm not ready!