Virago 535 tapping

https://www.youtube.com/watch?v=atmC99pWH7A&feature=share

I have a problem, there’s a tapping noise on the virago 535 1996 the back cylinder runs better than the front and I took spark plugs out the back was black but dry and the front was black but wet, I can adjust the richness but there’s defiantly something wrong here also if I take the spark plug Cap off the front cylinder when it’s ticking over it’ll stay ticking over but off the back cylinder but if I do it the other way round the bike would turn off