Reduce the correct timing
Photo souse from Chinese forums.
Open distributor cover. Push the ‘kick starter’ softly. See the ignition point. Make sure, thit open about 0.4mm to 0.6mm
You can reduce these screws to change the gap.
See flywheel. This is 6.
Then next photo. Loose this screw a little. DON’T loose too much. Make sure you feel a little tight, but can turning. A little damp. Otherwise, you cannot reduce well. The whole distributor will move.
switch on. Make the bike have electric power. The the distributor from left to right. Let the middle cam just touch the point, and see the spark. This is the correct timing. You can try some times, make sure that is the correct timing.
You can also release this, and reduce again & again.