The 17.5mm carburettor for your 50cc 2-strokes with a P40QMB engine is a perfect match. Its sleek, lightweight design made from high-quality aluminum alloy ensures durability and longevity. This carburettor is specifically engineered for Speedfight /2 and 50cc mopeds, so you can trust it to deliver optimal performance and power. The fuel mixer, compatible with this carburettor, is built to offer perfect fuel-air mixture, enabling your engine to reach its full potential. When combined with the engine's high-quality components, this carburettor offers an unbeatable combination of power, reliability, and safety. Say goodbye to rough idling or stalling issues, and hello to a smooth, powerful riding experience. Replace it when necessary to ensure your engine's optimal performance and longevity.