Any snowmobile built into the 90s. Any dirtbikes built into the 90s. Any chainsaw built today. How are a piston reed or case reed any less reliable than a piston port?
Piston ports which is what most dirt bikes are, is a terrible design, No amount of exhaust tuning can fix the Holes they have in their powerband. The reed valve design is significantly better. You also have to look at the ports timing which is different than outboards.
