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  1. #1

    rave valves on a 800 with 1mm over bore

    Do the rave valves need machined down for a 1mm over bore?

    I bought some used cylinders (suppose to have been stock 800 bore) and they are 1mm over size. I put the top end together with my rave valves from my stock bore cylinders and when I turn it over by hand with the head off it almost seems like the pistons just barley bumping the rave valve?

    how many cc is a 1mm over bore 800?

  2. #2
    2000 GPRXP 4tec shooter98xpl's Avatar
    Join Date
    Dec 2005
    Charleston SC
    yes, they need to be cut back. You want a .020 gap or a little more but no less. However you do 20 thousandths is what I am meaning.

  3. #3
    can I double the gaskets on the rave valve to step it back?

  4. #4
    "Tearing it up on the water" seadoobutch787's Avatar
    Join Date
    Nov 2007
    I wouldn't do that, just take a dremel tool and grind them back.

  5. #5
    So file or grind them down .020

    I was reading else where to take a calipers and scribe .020 across the end of the rave valve then file or grind it back?

    Is this the way to do it?

  6. #6
    Ok I took them to a machine shop and we took .025 off each one

    but when I got home and installed them they were still bumping the piston ring, so I took them out and took more off with a sandpaper paddle wheel and a drill until I had no bumping.

    am I going to be ok running these 1mm overbore cylinders? or am I asking for trouble

    when I bought them I was told they were stock but when I got them they are 83mm bores


  7. #7
    96XPSS's Avatar
    Join Date
    Feb 2006
    Warner Robins, GA Home of the 2007 All-Star Little League World Champions!
    83's are fine. My 920s ae 89mm, FYI.

  8. #8
    It got WIFI and touchscreen ! PWCGUY's Avatar
    Join Date
    Jul 2009
    I just doubled up on the rave valve base gasket which lifted the valve a little higher and seemed to get the clearance in the ball park without grinding the valve it self.

  9. #9
    2000 GPRXP 4tec shooter98xpl's Avatar
    Join Date
    Dec 2005
    Charleston SC
    Put some sealant on the gaskets so there won't be any leaks and you should be good to go.

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