[azjulian]

Hi - couple of questions on this

did you buy your demon new ? what I mean by that is do you know which primary and secondary jets you are running and are the symetrical right and left....

Have you checked that all your plugs are sparking properly / esp have you checked your dist cap is the engine running smooth ?

Have you checked your compression, do you have even compression on both sides ?

demon have 4 point adjustment of idle fuel mixture. after taking careful note of the settings of each of the screws ensure that they are all at the same setting. open them up on the pass side to richen and remove the backfire.

Also have you checked your float level settings on primary and secondary ? Too high would allow backfire, but would expect from both sides....