NEVER siezed an engine.
In all my years of riding 2 strokes, I've always kept them stock. Never played with jets, never monkeyed with pipes, ports or armchair tuning. I have never replaced rings (although my DT175 was overdue). I have NEVER seized an engine. Wide open running on beaches and river ice, rock crawling trials pace. Radiator only boils on long long climbs. We're talking about dual sport riding (which we used to call enduro) not race engines. I have found that reliability comes from not 'tuning' and modifying. I humbly suggest just riding and not worrying. The paved sections connecting trails are not freeways. When on the road, don't forget it's a dirt bike.