After every starting engine (cold) in the morning the engine is jerking very well. After a short time (30 seconds) of riding there is a fault message "backfire at cylinder 1". After clearing the fault message and reaching the operating temperature the engine runs very well.

The spark plugs at cylinder 1 were very tight.

Any experience to solve the problem?

Here are some pics of the spark plugs from cylinder 1 and 5 (for comparison only). The left ones are the spark plugs from cylinder 1.

 

well, your next option is to change to coil pack from #1 cylinder to another cylinder and see if the miss moves to the other cylinder. If it does, replace coil pack..

Do you get a puff of smoke on start up? I have seen injectors leak and slightly fill the cylinder with fuel and upon start up it shakes till fuel is burnt off.

but most likely your coil. you can also get new single plug wires from Mercedes

 

Sorry I forgot to mention that I replaced the coil pack (+ plug wires) from cylinder 5 to cylinder 1.
No there is no puff of smoke by starting. The jerking is prolonged than for a few seconds.
First at about 3-5 minutes the jerking is stopping.

 

Motor mounts maybe?

 

Try fuel injector

 

With a fault code and misfires?