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Old RM cylinder. Plated or not?


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Pretty sure most aircooled bikes didnt have Nikasil bikes, I would guess it will be sleeved.

Eric Gorr says;

"The Different Types of Steel-Lined and Plated Cylinders

There are two types of cylinder bores used on dirt bikes, steel or cast iron sleeves or ones with plating on the aluminum. Most dirt bikes made after 1989 have plated cylinders. You can check a cylinder with a magnet. If it sticks to the bore then it is a sleeve. If it doesn't stick then it is plated. There are three types of plated cylinders, Kawasaki Electrofusion, hard-chrome, and nickel silicon carbide. There are several variations of the nickel silicon carbide process but the most common trade name is Nikasil. The nickel-based processes have many advantages over hard-chrome, Electrofusion, and sleeving. Nickel attracts oil and is an excellent carrier material for silicon carbide particles, a wear resistant material that carries the load of the piston. This material is electro-plated right on to the aluminum cylinder for the optimum thermal efficiency. Nickel can be honed with diamond stones which leave distinctive peaks and valley scratches in the cylinder wall which retain oil and provide a certain bearing ratio between the running surfaces of the bore. It's possible to rebuild a plated cylinder by fitting it with a sleeve. However you can expect to pay more for bore maintenance over the life of the bike, and lose thermal efficiency and horsepower. Plated cylinders are harder and last longer than sleeved cylinders. Kawasaki cylinders with the original Electrofusion coating or hard-chromed cylinders can be repaired with nickel plating or sleeving. Steel or cast iron sleeves cannot be nickel plated unless they are separated from the aluminum cylinder. The reason is that the pretreatment for the plating would disintegrate the aluminum. There are four companies that replate cylinders in the USA. The average price to replate a cylinder is about $200."

So I would second the magnet idea as confirmation

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