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85 XR200R/250R Piston Wrist Pin Size

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Does anyone know if there is a difference in the size of the Piston Wrist Pin between the 85 XR200R and 85 XR250R. I am thinking about boring out my XR200 and dropping in a XR250R piston but I am being told that the Piston Wrist pin size for the 200 hundred is smaller than the 250.

T

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I presume you have the 4-valve model. The 200 wrist pin is 15mm and the XR-250 is 19mm. That is a huge gap. The 250 also has a 74mm which is impossible to squeeze into a set of 200 cases. You are on the right track, just asking about the wrong piston. I build 250cc, 200 engines using a 70mm piston that has a 15mm wristpin. Never a dome, alwaya a flat top, and they will drag race side by side w/a CRF-250R, only no valve issues, and they are much lighter being aircooled. My CR/XR conversion bikes wiegh 208 w/a full tank of gas. I'm always building 200s that these guys are just "discovering" and have been making over 25hp for years. I'm building a 253cc TL-125 trials engine right now using the same 70mm piston. These "new" 150/230 "mods/discoveries", make me yawn and sometimes laugh. Clint

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According to WISECO , the 1984-1985 XR250 and 1984-1987 XL250 have a bore of 75mm, and use a 17mm wrist pin. The 1979 thru 1983 XR250 and XL250 have a 74mm bore, and use the 19mm wrist pin.

The 2-digit number in the wrist pin circlip number indicates the wrist pin diameter (i.e. CW17 is a 17mm wrist pin diameter size).

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bianese

Thanks for the information I really appreciate it. Yeah I have the 4 valve model and I want to boost the horsepower on it. It sounds like you have already done what I am trying to do. If you don't mind can you please share the part numbers of the piston, rings, and wrist pin that you used to build up your 200's.

T

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Hey, The cases will need to be bored and the cylinder will need a new liner for the 70mm piston. I use a special, slipper style piston that I will be glad to sell you. I can also do the machine work on your parts if needed. Clint

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