Ideally, it is recommended to maintain the engine oil level within the designated range specified by the manufacturer. If the engine oil level in your KTM 200 Duke is at the maximum level indicated on the dipstick or sight glass, it should generally be acceptable.
Excess oil can lead to increased pressure within the engine, which may cause issues such as oil leaks, reduced lubrication efficiency, and increased stress on engine components. These factors can potentially affect the overall longevity and performance of your motorcycle.
To ensure optimal performance and longevity of your KTM 200 Duke, it is recommended to follow the manufacturer's guidelines regarding engine oil levels. If you find that the oil level consistently exceeds the maximum level, it would be advisable to consult a qualified mechanic or the KTM service center to assess the situation and make any necessary adjustments.