Tom M Posted July 6, 2011 Share Posted July 6, 2011 Sorry for asking about a Kawasaki on a Guzzi site but this could happen to a V11 owner if they let their exhaust valve lash get too tight... I'm in the process of fixing an air cooled '83 GPz1100 that belongs to a friend. It had no compression in the #3 cylinder so I pulled the cam cover and checked the valve clearances. All were set (shimmed) to .002" except for the exhaust valve on #3 which was .001 or less. The valve lash spec for this bike is .003 - .007 so they were all set wrong by a local shop not long before the problem arose. I removed the head and set it down with the combustion chambers facing up and filled them with water. The water drained right out of the exhaust port on #3 but all the others held water overnight. I pulled the #3 exhaust valve and as expected it's burned and the valve seat has some crust on it. I want to repair this for the least amount of money that I can because the bike isn't really worth much. It will be put up for sale once I get it running. The shop did the valve adjustment years ago so I won't even bother asking them for help. My questions are: Do I have to bring this to a machine shop for repair or should I try and clean the valve seat up myself? If so, how? I don't know if the crust on the seat is just carbon or if burned valve residue. If I can clean the seat can I just lap a new valve into it? Thanks in advance to anyone who's been there/done that before Link to comment Share on other sites More sharing options...
Kiwi_Roy Posted July 6, 2011 Share Posted July 6, 2011 In my experience with old Brit bikes the valve will burn away before the seat because it is cooler. If you can lap in the old valve or a new one there's no reason the bike shouldn't run for years. My buddy has a pair of 70s KZ bikes that have never been touched with about 70k on the odo. Link to comment Share on other sites More sharing options...
felix42o Posted July 6, 2011 Share Posted July 6, 2011 I have no experience with a Kawi cylinder head in particular, but the valve seats should be hardened enough to take a good cleaning, then you should be able to lap a new valve in to match. Sounds good from my seat in front of the screen, anwyay. I'd certainly give it a go, as it couldn't end up any worse than it is for what you said about it's worth and running condition before hand. Link to comment Share on other sites More sharing options...
Tom M Posted July 6, 2011 Author Share Posted July 6, 2011 Thanks guys. Any ideas on how to clean the valve seat? Are they usually hardened steel or something softer like a bronze alloy? Would a little wire brush on a dremel tool be too harsh on the seat? Link to comment Share on other sites More sharing options...
Baldini Posted July 6, 2011 Share Posted July 6, 2011 I burnt a valve on my old roundhead. Cleaned up the seat, new valve & lap was fine, still is far as I know. Can't remember what I used to clean up the seat. Dunno what they are made of, but whatever comes to hand within reason, if you're slow & careful with it I woulda thought it'd be OK. KB Link to comment Share on other sites More sharing options...
gstallons Posted July 6, 2011 Share Posted July 6, 2011 You want to perform the cylinder or valve leak test with kerosene or diesel. These two fluids will leak where nothing else will. Find an independent machine shop that will understand your situation.. See if they will reface the valves and seats on that cylinder. Link to comment Share on other sites More sharing options...
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