Hi mate, yeah it is a 4 Stroke It got serviced last year after i just got it, the guy who done the servicing who deals specially in Chinese scooters/bikes said he thought it was a 50CC. He said it wasn't until he looked at the tax disc he saw that it was a 125CC and even then he had to size up one of his 125cc Carbs to mine to see it was a 125, he says he doesn't understand why it's so slow and that the clocks only go up to 50 for, he showed me that all his 125s all have bigger clocks then what mine does (No he didn't try to sell me one) When i start to get near 50, downhill and wind on my scooter it will start to jerk every now and then...Which is how i can tell i'm going to make it to the 50MPH mark. EDIT: Not due a MOT till sometime next year (still within 3 years)