Topic: backfiring only on one side??

[dysfoundation]

ok so cleaned out the carbs and adjusted the valves got the bike to idle but now its backfiring from cylinders 3 and 4...
i thought it was a combination of dirty spark plugs and seafoam in the gas so i completely drained the bike and chainged the filter and plugs...but its still backfiring im lost on how to fix it

[camelman]

What is your exhaust configuration?  It sounds like you have crud in your carbs.

[dysfoundation]

i just cleaned them out..but could it be from adding marvel mystery oil?

[camelman]

We need more info first. It isn't always what you think, which us why you are asking us.  We've all been there before.

What kind if bike and what is your exhaust configuration?  Four into one, four into two, four into four?  Did you get your emulsifier tubes out to clean them?  Are your mixture screws set to factory settings and are the carbs bench or vacuum synced?