The points cam is driven by a plastic gear that can disintegrate. Using a spanner to turn the points cam (rather than removing the plugs and turning the motor by hand) can overwhelm this weak gear.
Check the stop-valves on the twostroke oil lines. They are liable to stick if the bike is left sitting. As a result, the crankcases can fill with oil and hydraulically lock the engine when started, bending a conrod.
If any of the triples’ engines has been left standing for months, take out the plugs and turn the engine over quickly. If they spray out oil, the oil-line valves need replacing. The springs particularly can become brittle and fail.
Mild state of tune and small carbs smooth out the GT380’S power delivery