I met Max at Donut Derelicts a year or so ago when he rode up on his motorized bike. He runs with a bunch of his friends aged 13 to 17 or so and most of them ride motor bikes. Max is the most mechanically inclined and keeps most of them running. His gang likes to take long rides together and also play on the banks of the Santa Ana river and go off roading at Sheep Hills. Some of them have gone through multiple engines and tons of parts. Max has made a lot of engines from parts to keep on the road. He also has a 4 stroke 49cc bike and a Briggs bike I helped him build. His dad owns 3 classic cars and Max helps keep them running also. As some of his buddies get drivers licenses, they drop out of motorbicycling. Max has another year or so to drive legally but has already learned how and has mastered a stick shift.
I've taught him how to clean up the appearances of a bike with an engine kit by shortening cables, custom clamps, tensioner deletion, wire loom, etc. So installing stock kits may seem a step backwards, it may lead to custom builds for a lot better pay.