The Suzuki Swish 125 makes noise when accelerating because of the way the engine works. The engine is designed to provide more power when accelerating, which leads to higher RPMs, or revolutions per minute. This increased speed causes more friction between the internal parts of the engine, resulting in a louder noise. Additionally, the exhaust system in the Suzuki Swish 125 may be slightly clogged, which can also increase the noise when accelerating. To reduce the noise, you should get the engine checked and serviced regularly and ensure that the exhaust system is in good condition.