Kawasaki KZ650 cafe-racer. About bolts and gaskets.

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!

Rectangular cuttings for timing chain idler gears’ shafts turned out to have a shape that is far from rectangular:

Another side of gasket didn’t look better:

I put this Wiseco cylinder gasket on  its place and found out that the position of two gasket’ metal rings from four were far from perfect too. Moreover, the gasket was visibly sticking out beyond outlines of cylinder block or cylinder head.  It happened that I had a Kawasaki used KZ750 cylinder head gasket, so I placed it atop of the Wiseco gasket and positioned them both with dowel pins. As you may see in the photos below, the Wiseco gasket’ outline is a few millimetres larger than the outline of the OEM gasket.

Sure, I have no use for the gasket that has such issues. And it was a pretty good lesson  too: to check parts even if they came from a manufacturer you already trust.  I had no choice but order the Kawasaki OEM gasket, and I already ordered it. But that’ another story which I’ll tell later.

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