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Xr250 Piston Swap

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I have an 1988 XR250 I am restoring. I noticed the 1986 and on motors have a 73mm bore and pre 1986 have a 75mm bore. Has anyone had any problem putting a 1985 piston in? My 1988 cylinder is gouged too deep to bore .020 and I have a 1985 piston I could put in. The 1985 cylinder is identical to 1988 except for larger bore. It will bump my cc to ~267. Thanks

Gerald

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This is exactly what XRs only used to sell for their low compression xr280 kit in the late 80s - 1985 honda oem piston. I think they used the second overbore piston - which left you with two overbores after that. I have used this piston in 86, 87 and '94 XR250R motors

I love this piston in the bike for the bottom end boost. It bumps compression slightly. It will pull taller gearing with this piston - I used to go up one on the countershaft and it would pull really well - even in tight woods. It was really, really fun to ride.

The stock piston is much lighter and has lower compression. This piston is heavier and with higher compression. Just letting you know that you will trade off the rev-ability of the stock motor for low end grunt.

Given that you already have this piston - I would go ahead and use it. If I didn't have this piston already - I would go buy the J & E piston that bumps it to 277cc.

- jeff

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