10-23-2009, 05:00 PM #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?
10-23-2009, 08:59 PM #2
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.
10-23-2009, 09:29 PM #3
10-24-2009, 08:32 AM #4
I wouldn't do that, just take a dremel tool and grind them back.
10-26-2009, 12:32 PM #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?
10-26-2009, 04:34 PM #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
10-26-2009, 05:46 PM #7
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83's are fine. My 920s ae 89mm, FYI.
10-27-2009, 11:10 AM #8
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.
10-27-2009, 05:03 PM #9
Put some sealant on the gaskets so there won't be any leaks and you should be good to go.
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