My neighbor was a motorcycle mechanic for about 30 years of his life, so when he saw i bought a 400xs special, he offered to help me work on it. At the time, the left wasn´t running as strong so we changed the spark plugs, no change, after cleaning both carbs, the left now backfires occasionally, this has stumped the mechanic. He said he saw water in the gas tank and i was wondering if this may have anything to do with it. anyones thoughts are helpful and they can email me at fallen40379@hotmail.com or post on here to send me their ideas as to how to fix it. Thanks