As for your other questions
No idea
Probably not too long. 2 stroke trail bikes are slowly being fazed out by 4-stroke sh*t heaps. Jet skis are slowly moving to supercharged and turbo 4 cly 4 strokes. 250GP will become 600's one make engine class. Snow mobiles Im not sure on (no alot of snow in Queensland AUST). 2 strokes are still the engine used by most karts around the world however
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