I have a 81' xs 400 and when I let off the throttle at high speeds it tends to let out a single and very loud backfire. This is the only time it really backfires. Is this normal or is there anything that I can do to stop this? Also another question to all those that own similar bikes, this is about gas millage. I get about about 100 miles out of the main tank (not including the reserve), does this seem like what the norm should be for this bike? I seems low for a motorcycle but this is my first motorcycle, so it could just be me being naive about motorcycles.
thanks