What Are the Causes of Overheating in Motorcycle Engines?

[OSpencer]

Motorcycle engine overheating can be caused by factors such as improper break-in for new or overhauled vehicles and incorrect maintenance and assembly processes. Here are the specific details: 1. Neglecting the break-in period for new or overhauled motorcycles: New motorcycles or those that have undergone major repairs have rougher component surfaces, certain deviations in part geometry and assembly positions, and smaller contact areas in friction pairs. This results in higher pressure per unit contact area, accelerated wear, and increased heat generation from friction. 2. Improper maintenance and assembly techniques: Severe wear on the big-end bearing of the engine crankshaft or improper installation of left and right crankshaft bearings can cause the vertical centerline of the crankshaft assembly to deviate from the cylinder block center after installation. This misalignment leads to lateral tilting of the connecting rod and piston wobble within the cylinder, causing uneven wear on piston rings and cylinder walls, reduced cylinder pressure, and ultimately engine overheating. In four-stroke engines, significant wear on the camshaft lobes or insufficient cam height reduces the exhaust valve lift opened by the cam rocker arm, obstructing exhaust flow. Inadequate exhaust volume then contributes to engine overheating.