1982 virago 920 front cyl backfire

Hi all. I just got a 1982 virago 920 and its backfiring at idle an slow speeds. That chugging at low speed is irratating. I pulled the carbs, tore them down and cleaned them although they were pretty clean anyway. Checked all the vacume lines..good and no leaks anywhere. Idle mixture screw changes nothing. I can hear and feel the backfire on that front cylinder..ie thru the vacume lines on intake that run to the mixture control valve, which seems to be an outlet for that backfire air. I called a local shop that works on older bikes and the guy said he had 2 of them just came in with the same problem. So...must be common and I hope someone can help me with this so I dont have to pay their labor prices!!!

thanks thomas  

I just joined the forum today. I think that I may be having the same problem. I have a 1995 Virago 535 and it backfires if i am in low gears. First and Second. My husband seems to think that it has something to do with the rear end.