The Yamaha MT-15 is a popular bike, but there are a few issues that have been reported by owners. One common issue is that the engine tends to vibrate a lot when running. Another issue is that the bike has a tendency to overheat in hot weather. There have also been reports of the brakes being unreliable in wet conditions, and the suspension not being up to par with other bikes. Ultimately, the MT-15 is a great bike, but it’s important to be aware of these common issues before you purchase one.