If you're experiencing a rattling or knocking noise coming from the front sprocket or driveshaft/countershaft area when accelerating on your KTM Duke 125 2019, it could indicate a few potential issues. Here are a couple of possibilities to consider:
Loose Front Sprocket: The front sprocket is connected to the countershaft, which transfers power from the engine to the rear wheel. If the front sprocket becomes loose or worn out, it can create a rattling noise when torque is applied during acceleration. Check if the front sprocket is securely fastened and inspect it for signs of damage or wear. If necessary, consider replacing the sprocket and ensure it is properly tightened according to the manufacturer's specifications.
Worn Chain and Sprockets: A worn or stretched chain, as well as worn sprockets, can lead to a rattling noise during acceleration. Over time, the chain and sprockets can wear out, causing increased play and misalignment. Inspect the chain for signs of wear, such as stretched links or damaged rollers. Similarly, examine the rear sprocket for signs of wear and ensure it is properly aligned. If the chain and sprockets are worn, it is recommended to replace them as a set to maintain proper functionality and reduce noise.
It's important to note that diagnosing and resolving mechanical issues is best left to trained professionals. If you're unsure about the source of the noise or how to address it, it is advisable to take your KTM Duke 125 to an authorized KTM service center or consult a qualified mechanic for a thorough inspection and appropriate repairs.