Determining the right rear sprocket size to increase the top speed of a KTM motorcycle depends on several factors, including the model of the KTM, its engine specifications, and your specific riding conditions. It's important to note that modifying the sprocket size can affect the bike's overall performance and may require adjustments to other components.
To increase the top speed, you generally want to consider a larger rear sprocket or a smaller front sprocket. This change will effectively increase the gear ratio, allowing the engine to turn fewer revolutions for each rotation of the rear wheel. However, keep in mind that this modification may sacrifice acceleration and low-end power.
For accurate and specific recommendations, I would suggest consulting the owner's manual or reaching out to a reputable KTM dealership or an experienced motorcycle mechanic. They can provide insights based on your KTM model and guide you on the appropriate sprocket size modification for your desired top speed increase, considering your bike's characteristics and your riding preferences.