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Fascinating! I see you been after this project for almost 10 years now. That's called perseverance.

Good stuff KB, keep going!

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winter's just around the corner here in Ontario Canada and that means for me that I have to make room in the garage for one vehicle which will severely limit my space for the bike. I decided today to pull the cylinder block off the engine and then pull the pistons so I can Cerakote the pistons before I have to teardown the table / sandblast cabinet / paint box.
So I pull the seat and the fuel tank off the bike and start looking at pulling the cylinder. Now I have to mention that for the past 10 years, the head has been off the bike and a plastic bag taped down over the open cylinders and I fully expected to find surface rust in the bores but to my surprise - spotless!!!

 

So I'm sitting on a stool looking around at everything and I happened to look up at the frame where #1 - #6 coil is located and the spot in the frame area is quite large and I'm thinking, would that 6 pack coil I got fit in that spot?? So off I go and find the coil and bring it up to the garage and try fitting it. Sooooo close but no cigar. But if I cut out the tray that the coils are mounted to and form up a bracket, I'll be able to sneak the coil pack up there in the frame and it will be up tighter than when the stock coils are all mounted up.

 
This is the spot where #1-#6 coil sits

 
6 pack coil sitting beside the opening. Looks like I'll have to drop the tray down about 30mm. Now looking at it, I think I can use a couple of drop down brackets and bolt them to the frame rails.

I had to remove the #1-#6 coil and no surprise the top of the coil was cracked. 65K on the bike. One of the weak points that causes everyone problems

 

Progress, even when slow, is still progress! Sell a car and work on the bike?

After rearranging the garage, I found a way to have the car in the garage and the bike in an area so I can work on it. Yippee !!

Cylinder block came off today. Note -  When removing the water pump drive shaft so that the camshaft chain is free, I found that doubling up the 12mm wrench to hold the shaft was a must to do in order to remove the bolt on the end of the shaft. One open end wrench on the shaft was not enough and the shaft spun in the wrench.
The cylinder block slipped off really nice and there's no rust in the bores, in fact the pistons were still wet with engine oil. Love it.

Pistons off now and rings removed. the 79 and 80 pistons only have 5 oil drain back holes and the later pistons have a second set of holes below the oil scrapper ring, so I will modify these pistons with the additional holes since there's a reported problem with oil consumption in the 79 and 80 model years, and I'm thinking that one of the permanent fixes was the additional drain back holes. 

I took the opportunity to measure the primary chain slack. I found that a vernier caliper worked great here. Measured down from the upper crankcase to the top of the primary chain and recorded. Then lifted the chain up with a 90 degree scribe while holding the vernier and recorded the number. The difference in the number is the slack in the chain. In this case I came up with .810" ( 20.6mm) I did this several times just to confirm and the numbers were all within .010" - .015" so I'm confident that the measurement is worthy of consideration. The service limit according to the Service Manual is  22mm, so here we are, engine top end removed and the chain is almost maxed out. Fortunately, about 8 years ago I spent countless hours searching for a supplier for replacement primary and secondary chains and ended up working with Ramsay Chains in the USA. I sent them a sample of the primary and secondary chains and they manufactured new chains for me. If I remember correctly, the new chains came in at around $500 CDN. So I have 2 new chains sitting in the shelf, so I guess it's time to bite the bullet and pull the engine and do the chains.

 
Stock 1979 pistons which have 5 drain back oil holes in the oil scrapper ring groove

 
Measuring the primary chain with the cylinder block removed

Working on the pistons today. Want to go bug eyed?? Try drilling 48 - 5/32" holes , (8 holes in each piston) for additional drain back for the oil scrapper ring.

 
4 additional holes on the front and back side of each piston to mimic the later model pistons

 
Although this is a ZN1300 piston, you can appreciate that in 1984 Kawasaki decided to add extra drain back holes, and it must be for a reason.......

Thanks for good info about oil consumption. My 79 burned from day one and just got worse. As in nearly a quart every tank.

What I don't yet understand, and don't tell me right away, I want to chew on it a bit, is why adding the holes work to reduce oil consumption.

My first rattle out of the box would be they provide an additional path to vent cylinder wall oil to piston interior, returning to crankcase. Which would infer that the return passages behind the oil scrapper ring is to restrictive, allowing oil to enter and burn in the combustion chamber?

More thinking to come.. I love things that make you go, hmmmm.