Since Kymco's unique way of throttle barrel/grip make it near/or impossible to use simple throttle stop such as NEP, looking thru my junk box found O-Ring I had used I believe on my Kawasaki Concours as throttle stop, tried it on XTown and works, providing friction between grip and bar end, when you want it. Simple and fairly safe.
O-ring, yellow is from Caterpiller, part number I forgot.
My book cheap/simple fix for long straight stretches.