I just bought a 68bsa and it is backfireing out of the right exhaust, it also seems that it doesnt do this as much when the bike is on the kick stand leaning on the left side. any suggestions on what this can be?

Assuming you have dual carbs, it is likely that the right carb is misadjusted. Either high float level or out of sync. With the bike on the side stand, the right carb is higher than the left and off level. Interestingly, both my Triumph T120 and Honda VT750 had some similar symptoms which cleared up after carb adjustments. Good Luck! Pat