The KTM 790 Duke is generally considered to be a reliable motorcycle, with a good reputation for build quality and performance. However, as with any motorcycle, maintenance and upkeep are important to ensuring its longevity. The yearly costs will depend on how often you ride and how you take care of your bike. Regular maintenance such as oil changes, tire replacements, and brake pad replacements can add up to a few hundred dollars per year. Additionally, you'll want to budget for things like insurance, registration fees, and occasionally replacing parts that may wear out over time. Overall, the yearly costs of owning a KTM 790 Duke can vary depending on a number of factors, but it is generally considered to be a relatively affordable motorcycle to maintain compared to other sports bikes.