On the Triumph, these are modified stock: cylinder head and crank. These are special order: rods, crank and rod bearings, pistons, rings, and pins, cylinders, head and base gaskets, valve seats, valves, springs, guides, keepers, tappet buckets, valves, cams, cam gears, clutch plates, clutch springs, ignition module, coils, spark plugs, exhaust system, intake manifolds, carbs, and air filters. Sometimes I wonder why it is called a Triumph on the entry sheet. "Mongrel" would be a better description. Do not feel like you are alone on this matter.