Hi,
I have a series 2 LI150 that was fitted with a series 3 engine sometime during the mid to late 60's, the first 3 numbers of the engine number are 767 which according to the Scooterlounge website would indicate it is an SX150 engine, however its prefix is 150LI. I am in the process of stripping it down for an engine overhaul, so, will check the gear teeth to see if I can work out what it is. If anybody has any information about this I would be very interested to hear. cheers