Kawasaki KZ650 cafe-racer. Polished clutch & breather covers.

Another batch of parts I polished for our Kawasaki KZ650 project engine. It so happened that once, rummaging through ebay I came across New Old Stock clutch cover. It looked like a good deal so I bought it. Factory  polishing was part of the mass production process thus it never intended to be brilliant, and sure, this clutch cover, being stored for 40 years, has got some number of scratches during its “shelf life”.  Here you may see how it looked in the beginning of sandpapering. Scratches and factory non polished areas are quite visible:

And that’s how clutch cover looked after course of dry and wet sandpapering:

Polishing revealed some unevenness of alloy, but it’s a pretty ordinary thing even for more modern cast parts. However, I was satisfied with result:

Kawasaki KZ650 polished clutch cover Kawasaki KZ650 polished clutch cover Kawasaki KZ650 polished clutch cover Kawasaki KZ650 polished clutch cover Kawasaki KZ650 polished clutch coverI was forced to work accurately  on lettering, since they are pretty thin, but result like this will do for me.

Kawasaki KZ650 polished clutch coverAnd talking of reflection, it was hard not to notice them during photo shooting:-)

Kawasaki KZ650 polished clutch coverBit closer:

Kawasaki KZ650 polished clutch coverReflection of my world:

And of myself:

However, let’s proceed to smaller parts, like breather cover or plugs for the main oil gallery. Here they are, plugs before sandpapering and breather cover already in process:

Plugs were pretty rough and since they have to be tightened by wrench, I couldn’t take much aluminum from them.

But the result looked much better even with such limitations.

Kawasaki KZ650 polished oil plugs Same I could say about breather cover. Here is it in comparison with another non treated KZ650 breather cover I have in my possession:

Kawasaki KZ650 polished breather cover Kawasaki KZ650 polished breather coverNot perfect since I didn’t sanded out all corrosion dots, but I think it will do:

Kawasaki KZ650 polished clutch cover Kawasaki KZ650 polished engine coversAt this point I ran out of parts for polishing because the ignition cover turned out to be beyond saving and this fact caused change in my plans about ignition and alternator covers.


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  1. Mihaly


    Do you have a “how to polish” post somewhere around here? 😀

    1. gazzz (Post author)


      Polishing” is 90% surface preparation and only 10% polishing itself. The better you prepare surface – the better is result. Usually I do it in this way: firstly I remove cast defects, seams and so on where it’s possible. This work I do with help of sandpaper wrapped around rubber blocks, delta sanders (have two of them) and Dremel. Then I sandpaper dry with sandpaper up to 800 grit manually and with delta sanders and Dremel. After dry sending I do wet sending (up to 3000 grit).

      Then it’s time for first polishing. I use various headpieces for Dremel for hard to reach places. For other cases I mostly use buffing cloth wheels installed on bench grinder. Once surface polished all defects (traces of sandpaper and so on) became visible. I remove those of them that could be removed and do second polishing.

      Some aluminum parts need to be polished long and in all directions to became perfect, while for other parts long polishing makes no good, as it exhibits tiny defects (like pores). Of polishing compounds I use two: mostly liquid Doctor Wax Metal Polish and solid past (supposed to be Diamond polishing compound , dunno of what concentration, but it works just good ).

      Here are some additional tips and tricks:



      1. Mihaly

        Thank you so much for the detailed reply!

        Keep on the good work

        Cheers from Hungary


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