After replacing the crankcase cover gasket and reassembly, there is a loud "klacking" sound when the engine turns.
I already checked that the balancer shaft is lined up correctly.

What else could be wrong ?

Any help is appreciated.

 

Update on the klack-noise issue: it is gone
The balancer shaft hit the piston rod once a turn which caused the noise. Otherwise the engine ran fine.
After consulting the service manual I double checked the balancer shaft alignment: the dots lined up as required.
So I experimented with offsets. Here is a picture of the current setting:

crankshaft vs. balancer setup
Engine starts and runs fine with now extra noise.
Can I just assume that I have a mislabeled part, or am I doing something bad ?

Any insight/help is appreciated