ORIGINAL: pe reivers
Looks like your ignition is locked in low voltage mode, and does not advance anymore. In order to test this, you have to turn the sensor about 22 degrees clockwise. Because now the ignition is fully advanced, the engine may kick back if you are careless.
If this fails, you can fit an RCexcl ignition as an alternative.
Many folks will gladly accept your ''boat anchor'' and make it run like it should. Just push the right buttons and that ''Czech piece of crap'' kicks butt.