KZ650 cafe-racer

Why to bother with blasting if head is new? For one thing, 1980 KZ750 cylinder head is factory painted. The shade of silver paint is mostly completely corresponds those of bare head. However, when one wipe cooling ribs with rag soaked in carburetor cleaner one may see traces of paint on rag. Another reason is that media blasting is the only way to be sure that paint will be applied on bare and non oxidized aluminum.

But danger of media blasting is media itself that in case of cylinder head with its blind ends of oil channels may cause havoc if even remains of it were left in some corner inside. So when I pack cylinder head for glass beads blasting I pack it tight. I pack all valve tappets’ wells with rags and closed all oil channels on upper side of head with paper tape. Then I sealed upper end of cylinder head with paper tape. I used old camshaft end plugs and I didn’t forget to seal tachometer port with piece of fuel hose with bolt in it.



Next layer is cardboard gasket:



Usually I use original valve cover as upon cardboard gasket, but configuration of KZ650-KZ750 valve cover may complicate the work of blaster, so I made cover from plastic I had at hand (some kind of monolithic PVC I suppose).

I “rag protected” intake channels:



Then I applied to them paper tape:



And similarly to top I covered them with cardboard gaskets and PVC covers (this time transparent).



Same procedure I applied to the bottom of head (I was careful with oil channels as I want no rag threads left there).

Exhaust ports I sealed with rags and plugs made of thick monolithic PVC in combination with paper tape for better sealing.





Old spark plugs finished sealing. In result I got something like cylinder head on legs…

I prefer to paint aluminum parts as soon as possible after glass beads blasting. So in the very morning of the day when I have to give cylinder to painter I mounted it to my Zephyr and rode some 20 km to glass beads blasting workshop. I was lucky: they took it in work immediately, so I didn’t have to wait for long, and relatively soon I was on my way back. I always take couple of pairs of new nitrile gloves with me when I bring parts for media blasting, thus after blasting I treat parts that will be painted only in gloves to keep them free of grease.

This time there was not much of difference between parts “before” and “after” glass blasting which is no wonder for new part.





I removed all covers and plugs, then “stretch filmed” cylinder head again and brought it to pain shop where it was painted with Eastwood Ceramic Engine Paint (Color: Universal Aluminum). I let cylinder head to dry for couple of days before I returned it to my workshop. My recommendation is to transport freshly painted parts wrapped in paper (to use paper as first layer of package). In case of storage or long time transportation all next layers of packaging also have to be penetrable for still evaporating solvent and do not react with it.

Eastwood Ceramic Engine Paint being used with its activator give 3/4 gloss surface. Fortunately it will reduce to semi gloss (mostly satin) after drying and baking. What else I could say about this paint? I like this shade of silver.

Cylinder head will lay drying on the shelf for another week. Meanwhile let’s talk about valve covers. The thing is that KZ750 (as well as later models of KZ650) cylinder heads unlike to early KZ650 heads have casts for emission control system channels. In bikes intended for countries without emission control those channel remained non-drilled and therefore cylinder head covers have kind of cap protrusions to cover casts on cylinder heads.

Original cylinder head of my KZ650 is of early type and has no casts for emission control and therefore its cover has no “caps”.



Without those caps bare casts on cylinder head look quite inaccurate so I decided to buy KZ750 valve cover.



When it arrived I found out that main difference between KZ750 and KZ650 covers is not pins for upper cam chain’ guide (easy to remove in fact):





, but different design of camshaft ends:





Here is what I mean:

And it turned out that I like design of KZ650 valve cover so much, that I couldn’t force myself to install KZ750 valve cover on the engine of our project. At this point you may assume me to be mad, but for me it was just a matter of fact: I needed to work out other solution. So I dug for information dipper and found out that there was KZ650 valve covers with design similar to early ones but with caps for emission control system’ casts. They were quite rare and those for sale were mostly all in Canada (it seems they were designed for Canadian KZs), however I managed to find couple of them in Europe. It took some time to find suitable valve cover as most of them looked even more oxidized than original valve cover of our engine, but in the end I found what I needed in Austrian ebay. That valve cover was already media blasted (glass beads- or vapor-blasted) and looked pretty decent. Here are photos of it as it arrived.







As you may see it’s similar to early cover but have “caps” to cover aforementioned casts on cylinder head.

And while I was comparing all covers and fit them to cylinder heads I found out that there is third difference between KZ650 and KZ750 covers: the distance between holes of their front and rear bolts is different. In fact KZ650 cover for 3mm shorter than KZ750 cover.





All valve cover holes have 7mm of diameter and for KZ650 center-to-center distance between rear and front holes is 255mm while for KZ750 it’s 258mm. On practice it means that I have to machine both holes on KZ650 valve cover for one millimeter each to install it on KZ750 cylinder head. However it’s not a big deal.

Original exhaust holders I’ve got with the engine definitely saw better times.



I could clean those oxidations and polish holders, but it would be quite a lot of work, so I decided to look if I could get replacement parts . It turned out that the exhaust holder of early design (part number 18069-061) was superseded by a more recent version (part number 18069-1006) which design I didn’t like. So I dug through ebay and found a set of four New Old Stock exhaust holders of desirable design in Germany. Three holders from the set were still in original packaging, while one lost its package during years of storage . Here they are:



Note the sticker. As you may see, it dated by 24/01/1979:



Meanwhile all holders still look like new, even this one without packaging. This is a clear demonstration of the fact that parts might be stored for more than 40 years without being damaged in any way.

Two of holders marked with number “1” and two with “2”, however there is no visual difference between these holders. Very cool design, anyway.

The second parcel contained chrome plated M6 bolts.



To be precise, there were 44 bolts are of five types:





It could be easy to guess what these bolts are for – for those, who are familiar with Kawasaki 650-750 air cooled inline fours. As for others, well, they have to wait until my engine will be assembled:-)

Chrome plated cam cap bolts doesn't sound right. The original cam cap bolts are hardened so make sure your replacements are also or you may have issues.

No eBay APP ID and/or Cert ID defined in Kunena configuration

Chrome plated cam cap bolts doesn't sound right. The original cam cap bolts are hardened so make sure your replacements are also or you may have issues.

As far as I could judge they are chrome plated and they are original KZ650 cam cap bolts, so I am sure they will be OK. I assume that early KZ650 cylinder heads were equipped with such bolts. Like this NOS 650 head: