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Pitted cams - is this normal?

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    #1

    Pitted cams - is this normal?

    Hey guys,

    This is a copy post from my build thread but really haven't gotten much feedback so I'm reposting here to hopefully get some answers. Anyway, I bought this 1988 GSX 600 motor recently for a engine swap project. I wanted to take a look inside before pulling the 550 in my '82 katana. The motor had 11k miles on it. Looked clean except for the following cam lobe. There's one other cam lobe that has the streaking but no pitting. Both are on the exhaust cam. I'm just trying to ascertain if this is a metal defect from the factory or something caused by neglect or abuse and is the cam shot or can it be run like this? I did a search on the net a found only a couple of threads with varying answers. If it's a metallurgy issue then I feel better about it. If not, then I'm probably going to have to open the engine up even deeper for inspection. Thanks for the input.

    1982 GS550M Rebuilt Winter '12 - 550 to 673cc engine conversion.
    1989 Kawasaki ZX-7 Ninja
    2016 Ducati Scrambler Full Throttle
    Tags: None
    #2
    Definitely not "normal". I would not consider running an engine with cams in that condition.
    Komorebi-The light filtering through the trees.

    I would rather sit on a pumpkin and have it all to myself than be crowded on a velvet cushion. H.D.T.

    Comment

      #3
      Normal, no. Not that uncommon though. Some motors are more liable to this than others. The early 16V Kawasakis do it a lot for example.
      What seems to be the sequence is, condensation causes a rust spot which if the motor is left long enough before starting again, becomes a pit. Once the surface is not uniform - and there are pieces of cam floating around - wear accelerates.
      I'd look for a cam in better condition. Most cam grinders offer a build up and regrind service if you want to go this way. Whichever way you go, the follower for this lobe will need either resurfacing or replacement.

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        #4
        Same thing happened to me on a race bike. I used an oil that "formerly" had a suitable ZDDP content that the new formula lacked. Ruined a cam and rockers. Megacycle to the rescue for a replacement cam and re hard-faced rocker.
        Don't use it as-is. More destruction is sure to follow. Paul

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          #5
          Ok that's what I was afraid of. That's some deep pitting all the way around the lobe which seems very unusual for a sitting rust issue don't you think? Either way, Looks like I'll need to find a replacement.

          Is it ok to put in a used cam and use the existing followers?
          1982 GS550M Rebuilt Winter '12 - 550 to 673cc engine conversion.
          1989 Kawasaki ZX-7 Ninja
          2016 Ducati Scrambler Full Throttle

          Comment

            #6
            Ideally, you replace cam and followers as a set. If you find a used cam complete with followers, there's no guarantee they'll go back onto the same lobes...
            Find a good cam and get your followers refaced.

            Comment

              #7
              Originally posted by Sci85 View Post
              Is it ok to put in a used cam and use the existing followers?
              No. It's just like changing your old drive chain for a new one... and not changing out your sprockets too. The newly installed component just gets chewed up and spit out by the old worn out part. Best to install matched parts in matched sets.

              If your exhaust cam is toast, best bet is to replace the exhaust cam and all the exhaust rockers. Sorry

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                #8
                One reason a lot of people use a top end oilier// That rocker and cam are toast !!!

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