[Ariel Red Hunter]

On running in (also called breaking in). There are people who don't believe in running in an engine, transmission, or brakes. But I do. And so, for those who agree, let me quote Ariels little book. "Proper running in of the new engine is of the utmost importance, as misuse during the first few hundred miles will (today we can say may) lead to poor results, and unnecessary expense. Definite running-in speeds cannot be given, as the safe limit of speed absolutely depends on road conditions, etc. Keep the engine turning over easily on small throttle openings, letting it rev, rather than pull slowly on large throttle openings. All motor cycles leaving Selly Oak are in first class condition, but we have to leave the running-in to you. What your engine ultimately becomes depends on YOUR care during the first 500-1000 miles (on a Hawk the 500 mile mark means the engine is broken in). Give yourself lasting satisfaction by using restraint until the piston and cylinder have become seasoned by constant heating and cooling and have acquired first class bearing surfaces and well-fitting rings. During the first few hundred miles running, check all nuts, bolts, screws and spoke nipples, etc, for tightness as parts will bed down during the running-in period thus causing slack bolts, etc. An upper cylinder lubricant (such as Marvel Mystery Oil) added to the fuel will assist valve lubrication and may be used throughout the life of the engine.
It is advisable to change the oil at the 200 mile mark and at 500 miles (for the Hawk) in order to remove any traces of metallic particles and foreign matter which may be liberated during the running-in process"...ARH