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98 kx250 cylinder repair options?

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I'm looking at a 98 kx250 that seized. I have not seen it yet but the owner says the cylinder is scored. What are my options? Can I have it bored oversize and fit an oversize piston? Do I need to have it replated? Did they use electrofusion in 1998? I'm not going to race, just trail and woods riding.

Thanks

Dave Cover

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The 98' was electrofusion not plated. Look at the cylinder and see if it can be cleaned up or have it overbored.

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Nikasil, Electro Fusion, Chrome Plated all the same...mostly. They are the same in that they are not a cast iron cylinder that can be bored to a larger size without being replated.

Max Power, Millenium, Lancourt, madmanengineering, US Chrome (in that order...IMO) repair and replate cylinders. If it's truely scored then it will require replating.

Many times what looks like scoring is actually just alum. deposits that can be remove with a lot of elbow grease and a scotchbrite pad.

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Electrofusion is a type of plating.

If it is damaged, have a replating company repair and replate it. You can not just overbore a plated cylinder, like an iron sleeve.

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Have the plating bored off the cylinder wall, 2mm overbore and replate.

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Nikasil, Electro Fusion, Chrome Plated all the same...mostly.
Not true. They are hugely different processes, with very different qualities.

While Porsche and Yamah did experiment with chrome plating, chrome plating is not used in ANY modern engines that I am aware of. It's use tends to be limited to things like hydraulic cylinders and Harleys.

Electrofusion is a process whereby a hard metal coating is welded onto the bore surface with multiple electrodes at the same time, and then machined to the correct bore size. Kawasaki used molybdenum for the electrofusion plating. While much harder than a cast iron bore surface, it is still softer and thinner than nicasil.

Nicasil is now the coating of choice for most manufacturers of high-performance engines. It's a composite of nickel and silicon carbide, and is essentially "sprayed" onto the bore surface. It is harder and more durable than electrofusion coatings, and has excellent oil retention properties.

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Not true. They are hugely different processes, with very different qualities.

While Porsche and Yamah did experiment with chrome plating, chrome plating is not used in ANY modern engines that I am aware of. It's use tends to be limited to things like hydraulic cylinders and Harleys.

Electrofusion is a process whereby a hard metal coating is welded onto the bore surface with multiple electrodes at the same time, and then machined to the correct bore size. Kawasaki used molybdenum for the electrofusion plating. While much harder than a cast iron bore surface, it is still softer and thinner than nicasil.

Nicasil is now the coating of choice for most manufacturers of high-performance engines. It's a composite of nickel and silicon carbide, and is essentially "sprayed" onto the bore surface. It is harder and more durable than electrofusion coatings, and has excellent oil retention properties.

can it be honed (nikasil)

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If you send it out for replate, seriously consider Millineum Technologies. They did a superb job on my cylinder for my '00 KDX200. Just send them the cylinder with a new piston so they can size the bore accordingly.

Little Jeff

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Not true. They are hugely different processes, with very different qualities.

...

The point is none of them can be overbored as they are all a coating on the bore--Not like a cast iron cyclinder or sleeve that can be overbored. That is the only pertinant information regarding the question to this thread. Hense the statement that, "Nikasil, Electro Fusion, Chrome Plated all the same...mostly" Maybe you missed the mostly part? But, thanks for the expanded lesson.

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The point is none of them can be overbored as they are all a coating on the bore--Not like a cast iron cyclinder or sleeve that can be overbored. That is the only pertinant information regarding the question to this thread. Hense the statement that, "Nikasil, Electro Fusion, Chrome Plated all the same...mostly" Maybe you missed the mostly part? But, thanks for the expanded lesson.
Understood.:thumbsup:
can it be honed (nikasil)
You can (carefully) run a ball hone through the cylinder to clean the glaze, but that's all a hone will do to nicasil. An aluminum oxide hone is incapable of cutting any metal from a nicasil bore, so if your cross-hatch is not clearly in good condition after cleaning the bore surface, the plating is worn out.

All you really need to do is to clean the bore surface with warm soapy water and a Scotch-Brite pad.

If you choose to hone a nicasil bore surface, use only a ball hone. The square edges of a finger hone can catch in the port windows and damge the plating at the edges.

DO NOT hone an electrofusion cylinder (pre-'03 KX 125 and 250, all KDX and KX60/65/85/100 cylinders). The electrofusion coating is much more susceptible to chipping and flaking than nicasil.

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You can (carefully) run a ball hone through the cylinder to clean the glaze, but that's all a hone will do to nicasil. An aluminum oxide hone is incapable of susceptible to chipping and flaking than nicasil.

tkx it help. i think im gonna go for a replate

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