My Zephyr 750 ownership. Part 3.

Okay, let’s continue interrupted line of story about my Kawasaki Zephyr 750 owning experience. All photos used in this part of story where made and processed  in 2009 and I suppose they a still good enough to avoid searching them in archives and  reprocessing.

In the year 2009, one May morning I was on the way to home and almost reached the point of destination when suddenly the engine of my Zephyr began to sound strangely. There was less than one kilometer to my garage left, so I rode right to it, then I got off the bike, slightly twisted the throttle, took a look at my exhaust and understood quite clearly: shit happened…

The left muffler smoked constantly and thrown  out a huge cloud of smoke every time when was throttled. By the colour of smoke it was obviously an oil.

I stopped engine, turn out spark plug from first cylinder and saw such a beauty. I was tired after road and hugely amazed by what had happened, so my mind even didn’t caught what I saw.

img_3462I untied a luggage, rolled Zephyr into garage, put the spark plug in the pocket and walked home.   Only after the lunch and half an hour later, after getting some rest I took the spark plug again, looked at it and understood that the strange coating covering it is nothing else, but aluminum originated from the piston…

Of course, in  half an hour I was back in the garage  and this time I was armed with flashlight. I looked through the spark plug bore  into the cylinder, and there it was, huge hole with melted torn edges right in the center of piston dome.

Okay, I’ve got a problem so I had do find out the solution. I pulled off the cylinder head and that’s what was there: the holey piston in cylinder number one and piston with craters in cylinder number two.

img_3479 img_3483As the reason of this disaster I tended to see the combination of poor quality of fuel (I filled the tank on “no name” rural gas station last time) and breakage of insides in left exhaust muffler. I found out that the baffle in left exhaust broken off which  might  caused a lean fuel mixture for first two cylinders.

To repair the engine I had firstly to place orders for all parts, needed for it: gaskets, valve seals, pistons, of course, and so on. After  calculating the cost of four pistons, four sets of piston rings and original head gasket, I caught the idea that this price is quite close to price of Wiseco K810 forged pistons kit. Of course I have chosen Wiseco.

Garage in which I hold my bike in those time wasn’t mine. It was garage of my friends and couple of their motorcycles stood there, but garage itself wasn’t adapted for carrying intended repairs. So I began with garage preparation: cleaning, space organizing, lighting improvement and so on.

After all garage improvements were done, I could focus all my efforts on Zephyr repair. I pulled engine from the frame and placed it on the improvised workbench. I had a lot of work to do before my  parts orders arrived:

  • Cleaning up engine outside and washed out all melted aluminum from its inside.
  • Dissembling cylinder head, remove all melted aluminum from surfaces and valves, clean up carbon deposits from head channels
  • Grinding the valves

That was only a second Japanese engine I’ve got in work and in that time I hadn’t so many useful tools which now I have at hand.  But I did my best and here is photo as I made them in those old days, so you may see on each of them same part before and after treatment.

img_3783_ img_3790 img_3795_ img_3798 img_3808After all was cleaned I drove the cylinder head in special workshop where its surface and valve guides were measured. Measurements showed that  according to information in repair manual cylinder head components were in good condition , and valves seals arrived in that time so I grinded valves and assembled cylinder head.

Wiseco K810 kit arrived in a month after the order. It looked magnificent and cost every buck I spent on it.

img_3985 img_4017 img_3967 img_3963Cylinders were bored and on Jun 22, 2009. Everything  was ready for assembling, but I still had not received OEM cylinder base gasket four O-rings for oil system and set of new carburetor holders  . As we found out, my parts somehow stuck in Custom service in the beginning of June and just laid there for a month, so I got them only on July 9, 2009.  What was a reason for such “minor” delay, I may only guess, but all those days I cursed Ukrainian custom service every moment of my life.

But anyway, I didn’t wasted all those days and cleaned, painted and polished all parts of my Zephyr which weren’t treated before. I also repaired left exhaust muffler, so when last parts arrived I had only to assemble all of  them together.  Here is a photo of all parts before assembling:

img_4544And photos of engine assembling progress:

img_4624 img_4625 img_4637 img_4651After some time engine was ready to be installed in frame:

img_4664After valves were adjusted and all parts installed back on their places I rechecked everything again and Zephyr engine sounded again after two months of silence.

But after repair I had to start engine run-in procedure. It took a 3K kilometers with continuously increasing engine’ load and I pushed all run-in process in three weeks.  After that I changed engine oil and oil filter and my Zephyr with upgraded to 810ccm engine was ready to new adventures.

img_5126We were on the road again and that was a happy feeling …

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  1. Jens Søndergaard Rasmussen

    Hi gazz
    Did you use the wiseco top gasket or did you use an original zepyhr gasket?

    1. gazzz (Post author)

      Hi Jens,

      I used Wiseco top gasket.


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