I just put the last of the parts on my YZ400 it was totally rebuilt and I went to start it today I did the proper procedure and nothing so I checked the spark plug turns out it wasnt getting spark i used some sandpaper between the electrodes to clean it bam i get shocked and it was getting sparked im like ok so i put it back in the bike kick kick kick still nothing &%$#@!?..I put some started fluid in it BAM backfires &%$#@!!..spark plug was wet so it was getting gas. The carb is in good shape..possible needs new spark plug? any ideas!