hi,i recently got my yamaha virago 700,started after 3 yrs,im not a expert,just cleaned the carbs,nd new plugs,it starts ok,but when trying to rev,servere carb and exhaust back fire,All the carb settings were changed due to the cleaning and i need to know how to synchronise the carbs,and set mixture settings,may be that the prob??hope you can advise me,thanks.