How are the air cooled engines of motos with high fenders being protected from destruction by gravel spray? The delicate fins and even the engine cases themselves, I mean. For instance, if you're doing something like traversing the looooooooong gravel roads of Alaska what's to keep your engine from being sandblasted into powder? This TW200 has a high fender conversion; you can see from the immense volume of mud, and the spray patterns thereof, that while the high fender keeps the front wheel from locking it's also completely exposed the fins and cases. Air cooled dirt bikes and enduros have been using the high-fender-exposed-engine design for decades, so maybe blast from gravel spray really isn't an issue like I think it is, or is it genuinely an issue that the OEMs decided just isn't their problem?