Hi I'm hoping someone can help my 97 custom sportster just started running real bad and back fire on deceleration I thought it was bad gas I changed that front cylinder seems dead at idle I swaped plugs it stayed the same if anyone has expierenced this type of prob and has an answer I would much appreciate it thanks

 

Bad plug wire on front cylinder? That might explain the backfire on deceleration too. Maybe switch wires and see if it makes rear one go out.

John

 

Did you check to see if the plugs are getting spark?

 

There is spark at both plugs