 The warmer versions (such as the much-loved Starfire) were generally less robust, but their light weight, enjoyable handling and peppy engines meant that many people considered the hours of necessary maintenance a worthwhile trade-off.Many BSA unit singles were built, meaning there are few 1960s motorcycles with such a large supply of readily available spares.The tunability and ready supply of these motors, combined with their compact and light(ish) construction has also made them a popular choice for modern "Classic" competition.