Motorcycle Piston Ring Fit For Honda XR250 1979-1982 XL250S 1978-1981 Standard 74mm +25 +50 +75 +100 Fit For Honda XR250 1979-1982 XL250S 1978-1981 single cylinder offroad bikes, base standard bore 74mm with oversize options +0.25 +0.50 +0.75 +1.00 mm for engine rebuild machined rings match cylinder bore tolerance, clearance with corresponding oversize pistons; direct installation without filing or extra compression ring + oil scraper ring set trail , blow-by carbon buildup for long offroad life Tight uniform sealing reduces oil consumption, power loss from compression leakage restores throttle for trail riding oversize selections cover worn cylinder repair needs; for top-end overhaul, cylinder honing regular dirt bike