Hi baz. The A12 engine starts with 68 HP, so its difficult to pick up 10 kph . A 120Y should do 150 kph. To do that, use 4th gear, put your foot down and let it rev to 6000 rpm. If it has 13" tires it will go slower, it needs the revs to do 150. Make sure the engine is adjusted correctly and timed for 32 degrees total spark advance.