That engine is similar to mine, 1991 120 Looper (VJ120TLEIE). There are three adjustments that pertain to timing on my motor.
First is the threaded rod/tube on the starboard side of the engine that is connected to the top of the throttle linkage. That will adjust your timing and can be easily adjusted on the fly with the motor cover off. Threading it in(towards the rear of the engine) will retard the timing, threading out will advance it.
The second one is a stop screw behind the rod/tube that is responsible for controlling when the timing should
STOP advancing as you proceed to full throttle. Timing should stop advancing around 3/4 - 7/8 throttle. Threading it out(towards the bow) will increase the upper timing limit and vice versa.
Both can be seen in this picture.
The third adjustment is on the port side. My air silencer has an arrow pointing to it with 18? TDC printed on it. It is the idle timing stopper. It limits how "retarded" the timing
can be at idle. The more you thread it out(towards the bow) the lower your
base timing can be at idle. It has
NO affect on timing above idle. It can be seen in this picture, behind and to the left of the starter bendix. If the 1st timing adjustment is advanced too far(threaded out) then the 3rd adjustment will have no change which might be what your experiencing.
I'll get a better picture from my own engine if needed.
Also, that engine has the Quickstart function. Quickstart will advance the timing until the engine temp reaches somewhere around 110? F I believe. Each time you start it after warmed-up, it will only engage QS for roughly 4-5 seconds.
Hope this helps.
