So what does scotty and everyone who knows motorcycles think about modern Japanese twin engines like yamahas CP2 engine that don't use cast iron sleeves in the cylinders but instead use a type of aluminum reinforced with silicon. I heard its not the same as the spray on liners as Yamaha just casts it as a bare aluminum block with silicon in it. Do you think that type of engine can last? I tend to trust the Japanese engineers but am still curious.
Kevin Cameron at Cycle World just published an article which I think will start to answer some of the questions you have. He writes excellent engineering explanations. He addresses a number of bike engine issues, at least one every week.
https://www.cycleworld.com/story/blogs/ask-kevin/motorcycle-technology-and-military-aviation/
Look at almost any late-model motorcycle engine’s cylinder bore and you will no longer see the traditional (and heavy) iron cylinder liner. German engine-development engineers racked their brains for ways to boost power, equaling or exceeding the performance of Allied fighters. Their testing confirmed that by eliminating the iron liner, which conducts heat poorly, and applying hard, porous chromium plate directly onto an aluminum cylinder, they could cool hard-working pistons faster.
In the early 1960s, when Yamaha was confronted with high two-stroke piston temperatures causing outright seizure or piston-ring sticking from oil gumming, the Tuning Fork folks tried the same thing. First they tried anodizing the aluminum cylinder wall, turning it into hard ceramic aluminum oxide. When that proved unreliable they adopted hard but porous chrome plating, and by 1967 they had a durable solution. Current production motorcycle engines employ even more durable hard plating such as Nikasil to improve piston cooling and shed the 6 pounds that iron liners can add."
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Porsche was using Alusil and Nikasil I believe back in the 80s. The cylinders are aluminum, then plated, then machined to tolerances.
