85 XR200R/250R Piston Wrist Pin Size

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.


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

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).


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.


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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