1978 honda xl 125 backfire

[84atc200]

Hi i'm having an issue with my xl 125.When i kick strart it it backfires and won't start. i know timing is usually the culprit,my question is can anything else cause it to backfire when attempting to start it?

[oldskool83]

too rich, check plug find out setting of a/f screw and your jets

[84atc200]

Ok thanks for the help I need a manual, i have a 110 main jet in it.Its supposed to have a 102,i'm not sure of the fuel screw setting.I have it at 2 turns out.The idle jet is the factory one.