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  1. #1

    GP800 2001 rear cylinder loss of compression

    I've got 2 2001 GP800
    with rear cylinder issues
    did a comparison for compression
    the rear cylinders are lower for compression readings 120 psi vs 180 psi
    called around and spoke to a few yamaha dealers
    one of which warned of these models having issues with rear piston going out
    so now I'm wondering if any others out there have had this issue?
    if so has anyone determined a specific cause?
    can suggest which brand pistons to use as replacements?
    and a reputable source that overhauls crankshafts

    definately want the repairs to hold up be long lasting, etc...


  2. #2

    Join Date
    Aug 2007
    Rotterdam,NY & Moneta, VA
    i never heard of the rear cylinder loss on the 800pv. i know that the power valves can take out the motor if you dont put wave eater clips on them. mine has 192 hours on it

    180 psi seems extremely high compression. im pretty sure the stock compression on a 800 is far less it should be about 120 psi if im not mistaken.

  3. #3
    Join Date
    Jun 2007
    Lake Grove NY
    why did you do the test to begin with,was there a problem??180 is way to high,carbon build up or something takin up space in there,i'd pull the head

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