You timing is too far advanced. Retart you timing a bit, only make very small changes at a time. A manual would be handy. If I recall correctly you have to turn the Motoplat stator anti-clockwise.
Remove the flywheel
Loosen the 3 screws holding the Motoplat stator in place so you are able to move the stator around by hand, not too loose though.
Ensure piston is in the 1.2mm BTDC position.
The flywheel has little hole on the side that lines up with a hole in the stator. Find a object/rod with the same thickness as the hole so it does not wiggle around.
Mount the flywheel again without bolting it on.
Insert the rod/object into the hole on the flywheel and line it up with the hole in the stator.
[Whith the piston at 1.2mm BTDC and the holes lined up you timing will be 100%.
Fasten the stator screws with the stator in its new position, be carefull not to move it again. Mount flywheel and tighten nut to with torque wrench to spec.
You must ensure though that the piston is 1.2mm BTDC, use a dial guage to determine TDC, subtract 1.2mm and recalibrate dialgauge to give you a correct value for BTDC and then work on that.
Oh, one more thing, the FLYWHEEL NUT HAS A LEFT HAND THREAD so it loosens & fastens in the opposite direction !!!
Hope this makes sense.