The timing is set in the CDI box. There is nothing that you can do to change it, other than tinker with your ignition switch that has two gas settings, which are as I understand it, in fact two different timing settings.
When installing the stator it has a indexing line cast into it (a thin line that will be located at 12 o clock when mounted to the engine) and the starter/water pump housing has a pointer cast into it (you can see the tip of it thru the timing hole on the top). Install the stator so the line is lined up with the pointer on the housing being sure to be as close as you can.
After the engine is completely assembled (stator adjustment is done with flywheel removed) you can then check timing using a timing light. The manual says 29* @ 3250 RPM +/- 1.5* with the throttle position sensor disconnected from the carbs for the 04 800 rmk 159.