2 stroke motorcycles on very long journeys ?

At that mileage, i'd think about a fresh set of rings and a cylinder hone. On a long run, blow-by can toast a 2-stroke that is otherwise in good fettle. Heat is your enemy. Toward the end of a stint, ease off and give the power plant a rest. Ditto any time the bike seems to be laboring. Resist the temptation to run wide open into a headwind, or up a long grade. You might also want to carry a set of plugs one grade cooler.