Jetting Carbs

These are the two jets in the 1980 carburetors,

  When I bought the restored yellow 1980 CB650 Custom the seller told me that the carberators needed to be 'jetted' for the 4 into 1 pipes and that the high flow K&N air filters.  The bike ran OK but it needed to be choked to stay running but I bought it anyway.  I took the bike to the mechanics and asked them get the carbs in running order.  I brought in my carbs from my old parts bike for them to use if needed.  They put my old carbs on the yellow bike and it seemed to work fine so they gave it back to me.  I took it home and continued to work on it myself. 

These are the screw-in type main jets for CB650, the holder is above and the actual jet is shown below.

  I looked into what is meant by 'jetting' and I found that factory main jets size is 90, the jets in the carbs that were originally on the yellow CB650 were 110s.  I replaced the 90s with the 110s and the bike performed much better and didn't need to choked to stay running.  One of the byproducts of upping the jet size is that more fuel gets to the engine so I had to adjust the main idle down and 'sync' the carbs.  The bike worked pretty good, started easily was dependable but seems to sputter and backfire so I ordered bigger jets in an attempt to correct the issues.  When the 125s came in from Sirius I put them in the cabs and started the bike up.  The engine revved out of control so I hit the kill switch and started to turn down the idle a few turns, starting the bike and checking until things were under control.  Once I got the idle close to where it needed to be I synced the carbs.  I've had it out for a few rides and it is working the best it ever has, more power, less sputtering and backfiring, but I think that I am still going to try larger jets just to see if it solves all the issues.