KZ650 cafe-racer

After baking I take cylinder head for resurfacing to the same specialized workshop that successfully bored and resurfaced cylinders for my KZ650. Even being new, the cylinder head had some “storage” warpage (around 0.06mm) and points of corrosion on the contact surface (effect of non-proper storage accomplished by the seller, Siegfried Spängler from Motorrad Spängler GmbH). We took 0.09mm from the cylinder head surface, so the cutter only touched intake valve seats. I could order to take another 0.05mm, but I decided to not go farther, even if some corrosion point still remained. My reasons were based on my expert judgment as follows:

• The points of corrosion that remains are non critical and couldn’t implicit the work of the engine or its assembling.
• Cylinder head could still be decked farther and maybe someone someday will thank me for that.

What I liked and appreciated in the work of the guy from that specialized workshop is that he made all the work with me observing, and the way he tuned his machine: cylinder head surface is shimmering and cutter traces are mostly invisible.

That is a machinist that knows his aluminum alloys! Along with his cutting fluids... Incredible work, Gazzz!

Yes, I was glad to find a reliable workshop. Hope they will not disappear.

Meanwhile, yet one engine part is ready.

The Kawasaki KZ650 oil pump turned out to be in perfect condition, but it needed some cleaning. To clean the oil pump properly I completely dismantled it, down to removing the strainer.



I soaked oil pump aluminum housing in the same solution I used for cleaning crankcases. Result was pretty nice: housing became clean and bright.

Since the original gasket is already more than forty years old, I decided to check how the aftermarket gasket for the oil pump fits. This gasket came with a set of gaskets I’ve bought earlier, even before I started working on the KZ650 engine. Turned out that it fits very poorly and that’s about all you have to know about aftermarket gaskets. In the best case the chance they fit properly is 50/50.



So I ordered a new OEM gasket.



It, quite expectedly, fits perfectly:

Along with it I also ordered a new oil strainer, as the rubber of the old one became hard as wood.



I cleaned steel parts with a carburetor cleaner. I shot a traditional “exploded view” photo and proceeded to assembling.

Not much could be said about it. All that is necessary is a clean table and clean engine oil. I do not recommend assembling an oil pump on the fabric as its fibers may get into the pump. First came the outer rotor.



Then I installed a pump shaft with gear and pins.



Next was the inner rotor.

Which was followed by the oiled gasket.



After it I installed pump cover. I have nothing against cruciform screwdrivers and screws, be they of Philips, JIS or other types. Moreover, I have a set of such screws that I reinstalled more than 50 times and they are still intact. However, I also know pretty well that being untouched for a long time they could become PITA to unscrew. So I always replace them with Allen screws. In case of Philips or JIS round head screws – with Allen round head screws.



The last point in the assembling list was strainer installation. Being new it fitted without issues: smoothly and softly. Assembling was finished and pump was oiled and ready for installation.

However, it will sit on the shelf for some time, thus it’s better to storage it in the right way, packed and protected:

As I’ve already mentioned, the Kawasaki KZ650 engine is mostly ready to be assembled. However there were (and are) some obstacles that still keep me from assembling.

First of them was engine bolts. My initial plan was to clean, glass beads blast original bolts and re-plate with zinc. So one day I went to a company that provides zinc plating and gave them several dozens of prepared bolts: all degreased and glass beads blasted. Among them was a set of bolts for KZ650 crankcases. At first glance the result looked very nice. However, when I returned with a pack full of freshly plated hardware to my workshop and started sorting bolts, I found out that about 10% of it had plating defects. The defects looked like this:

I returned bolts with defects of coating to the subcontractor and they redo the work. But at this stage I already had my mind full of doubts if I should use these bolts to assemble the engine. It’s easier to replace bolts that fix side covers or other parts of smaller significance. However it’s different for bolts that hold halves of crankcase together: especially for those that are in the crankshaft area and are to be tightened in specific sequence. So I ended up ordering a new OEM set of bolts. Since my goal is not restoration, I didn’t stick to bolts of early design. Instead I ordered a set of bolts from Kawasaki ZR7 which are interchangeable with KZ650 bolts. Here is complete set of them:



8mm bolts have black coating:



While 6mm are zinc coated.

Another issue was cylinder head gasket. I have one that came with a Wiseco K700 piston kit and I was about to use it as I have had only positive experience using Wiseco gaskets. I measured all pistons before cylinders were bored but it happened that I didn’t give a the gasket that was in the set a second glance and let it lay as it arrived, factory sealed for a long time. I think it happened due to the reason I was sure in the quality of Wiseco products.

So more was my surprise when I decided to check how it sits atop of the cylinder block. It might have looked normal from some distance…



But when I took a close look at it the only question in my mind was “What the f**k!”. Gasket seemed to be cut out by a drunk worker equipped with a blunt chisel. Round holes weren’t round, and look at that oval ports for O-rings on the ends of the gasket!