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  1. #1

    Gp1200r piston/cylinder replacement

    My oil line came loose and fried my rear piston. We salvaged the cylinder, it is only barely larger than it is supposed to be. Our standard piston size is 80.012 and I'm not sure if we need to buy a larger piston or if it should be ok with the 80.012 that was the original. Also, if we buy one that is larger, do all 3 need to be the same size? Any advice on this topic would be wonderful.


  2. #2
    PolarisNut's Avatar
    Join Date
    Dec 2006
    Lower Michigan
    You don't run oversized pistons in the 66V cylinders (unless they have been sleeved previously). You will need to send the cylinder to a place like Millennium Tech or US Chrome to have it repaired and replated...Will cost about $200. Check your crank bearings....they could be toast as well.

  3. #3

    Join Date
    Jan 2006
    Texas City, Texas
    Welcome to the forum.

    "Barely larger" is not quite descriptive enough. Did you damage your nicasil plateing? If it is damaged, then you should have it repaired/replaced. If it is not damaged, you can clean your cylinder with muratic acid if there is any material build up on the cylinder wall. After that, do a light hone.

    Contact the tech line at Give them the number stamped on the top of the cylinder (for example there may be a large number 12). Also give them the diameter of the cylinder wall if you think that it is significantly larger. They will hook you up with 1 of the 4 "standard" size pistons and rings that will match your cylinder.

    Check your crank and rod bearings for any obvious wear or burn marks. I would replace the rod bearing just because I'm there.

    As far as the other two cylinders are concerned, leave them alone if they look ok.

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