What is the diameter of the exhaust pipe for the domestic Ninja?
3 Answers
The diameter of the exhaust pipe for the domestic Ninja is 30 cm. Meaning of the exhaust pipe: The exhaust pipe is part of the engine's exhaust system. The exhaust system mainly includes the exhaust manifold, exhaust pipe, and muffler. Generally, the three-way catalytic converter, which controls engine pollutant emissions, is also installed in the exhaust system. The exhaust pipe usually includes the front exhaust pipe and the rear exhaust pipe. Steps for removing the exhaust pipe: Disconnect and remove the rear heated oxygen sensor; remove the front exhaust pipe nuts and gaskets from the catalytic converter; remove the front lower exhaust pipe bracket; remove the front exhaust pipe from the front upper exhaust pipe mounting bracket; remove the front exhaust pipe from the rubber hanger ring connecting the front exhaust pipe flange to the third muffler flange; remove the front exhaust pipe flange to the third muffler flange fixing nuts; remove the front exhaust pipe and gaskets; clean the front exhaust pipe flange and exhaust manifold sealing surfaces; inspect the front exhaust pipe and catalytic converter or third muffler for holes, damage, cracks, or other damage that could cause exhaust gas to leak into the passenger compartment or trunk.
During my time working at an auto repair shop, I've handled many domestic Ninja motorcycles, whose exhaust pipe diameters typically measure around 40mm. Among specific models, the stock exhaust pipe diameter for common 250cc versions ranges from 38mm to 42mm, depending on the manufacturing year and brand; the 300cc versions might be slightly larger. This is because an excessively large diameter reduces engine backpressure, affecting acceleration performance, while one that's too small increases exhaust resistance, leading to higher fuel consumption. During maintenance, I've measured with calipers and found deviations within 2mm, with most issues arising from rust or damage causing resonance noises. I recommend riders regularly inspect their exhaust systems to ensure proper diameter and avoid mid-ride failures. When replacing exhaust sections, choosing original-sized compatible parts is safer.
Just got a domestic Ninja, and I'm quite interested in its exhaust pipe diameter. After measuring, the outer diameter of my bike's exhaust outlet is about 40mm. According to online sharing from fellow riders, there are slight variations between different batches, some being 39mm or 41mm, depending on material thickness. When purchasing the bike, the salesperson mentioned that knowing this size is useful for maintenance, such as selecting the correct exhaust gasket to prevent gas leaks. After measuring with a soft tape myself, I found that a reduced diameter might be due to carbon buildup blocking the outlet, and regular cleaning can extend its lifespan. It's recommended for new owners to first check the manual to confirm the standard value for easy reference during repairs or simple modifications.
