1990 XT600 Rough Running

[Tioli]

I acquired a 1990 (marked on the headstock) bike that was non-running a few weeks ago. I got it running today. It is difficult to start (electric starter) and runs rough with occasional mild backfires. The engine wasn't rebuilt, it doesn't smoke. The carbs were knackered with broken screws and bits missing, so I sourced a fresher set from eBay. I haven't made any adjustments on the carb, just installed it. The exhaust is stock, but the air filter is K&N. I haven't replaced the spark plug or coil or spark plug wires. The airbox seems to be free of leaks, I did replace the carb holder boots between the carb and the manifold.

I'm not sure about the fuel/vacuum lines and haven't found a diagram to show me where everything goes. That might help.

So I'm asking where I might begin to make this engine run smoother and not backfire.

Thanks to all!

David