Is a motorcycle engine electroplated or painted?

[CarmenFitz]

Motorcycle engines are electroplated. Advantages of electroplating: Electroplating surface treatment technology can improve the wear resistance, self-lubrication, corrosion resistance and other properties of components by changing or adjusting the mechanical, physical and chemical properties of materials. Therefore, it is widely used in motorcycle metal and plastic parts, such as chrome-plated metal parts like the outer shell, wheel hub, piston rod, engine cylinder, handlebar, fender, rim, exhaust pipe, as well as plastic-based parts like scooter shells, instruments, trademarks, and model logos. Power source of motorcycles: Motorcycle power units all use internal combustion engines; engines that use diesel fuel are commonly called diesel engines, while those that use gasoline are called gasoline engines. Due to advantages such as light weight, small size, low noise and vibration, easy starting, and low cost, gasoline engines are generally used as the power unit for motorcycles.

[OAdeline]

I've disassembled and repaired quite a few motorcycles, and most engine casings are coated with high-temperature paint, rarely electroplated. Why is that? Painting is cost-effective and durable. When the engine is running, temperatures can soar to 200 degrees Celsius, causing ordinary electroplating to peel off quickly. The rough, matte texture you feel on the engine surface is a combination of primer and color paint, which provides both rust protection and heat dissipation. However, small parts like screws and chains often use electroplating for that shiny, attractive look. High-displacement engines might feature partial electroplating for aesthetics, but the main structure still relies on paint due to repeated thermal expansion and contraction of the metal—paint offers better flexibility.

[LeJude]

Last time I watched my friend refurbish an old motorcycle, the engine was taken apart and covered in patchy black paint. He resprayed it with three layers of high-temperature paint. Nowadays, most regular motorcycle cylinders use powder coating—epoxy resin sprayed onto aluminum surfaces and then baked dry, which is much more durable than traditional electroplating. Although chrome plating looks shiny, the exhaust pipe area tends to scorch and discolor from heat, while painted surfaces can last five or six years with regular cleaning of oil stains. Some modders insist on chrome-plating the entire engine, only to end up with cracks all over after a long trip, with repair costs high enough to buy a new engine.

[DiThomas]

From a materials science perspective, painting is more practical than electroplating for engines. Aluminum alloy engines first undergo anodization to form an oxide film, then are sprayed with special high-temperature paint resistant to 300°C. Electroplated layers accelerate metal corrosion under high temperatures, especially when exposed to acidic/alkaline moisture after rainy rides. Painting not only allows various colors to conceal casting flaws but can also incorporate metal powders to enhance heat dissipation. Those mirror-like Harley engines are actually multiple layers of transparent clear coat over metallic base colors - fundamentally still a painting process.