Originally Posted by hexnut
Honda made the 1st GY6.
Often repeated, especially on the internet, but nobody has ever come up with anything from Honda referring to a GY6, or parts fiches or service manuals about this motor. AFAIK, Honda produces service manuals and parts fiches for pretty much everything they make.
The first examples of the 50cc version I have seen came on the Kymco Filly. That is the only non-Chinese one I have seen that uses a 669 belt, and it has a design flaw, corrected in later Kymco versions but still in the Chinese versions, that is the primary reason you don't see many high mileage Chinese scooters that have not had the top end replaced. When China banned two strokes on their own roads, the 150cc GY6 was rushed into production, and there is an additional design flaw in the version the Chinese chose to copy which causes abnormally high crankcase pressure to build up.