'78 KZ 650 Refreshing/Upgrade Project

Such a small world sometimes isn`t it. Actually Mike sent along some shots of the Concourse not so long ago. Very nice looking machine for the money!

On another note, I`ve been digging around on Ebay/Kijiji a bit, thinking of going up a size, to 26mm Mikunis, instead of the stocker 24's that I have on now. Now, from my reading around, new boots from a KZ900/1000 with the same size carbs are the way to go? As in the spacing for bolts onto the head are about the same? I know this is a fairly common conversion/upgrade, but I want to check before ordering in parts etc....

I have to make another Z1 order pretty soon, and figure I'll throw in a set of correctly sized boots for 26's when I do so I am ready when I find a set of carbs to rebuild. (Anybody reading this have a set of vm26's they want to part with? :whistle: )

Anyway, some photos of recent paint work to come soon. Cheers,

Jonny wrote: . . . Anybody reading this have a set of vm26's they want to part with? . . . .

Would suggest a want ad in KZr Classifieds forum, where thousands more eyes will see it.

Good Fortune!

Done!

Thanks for the suggestion Patton. We will see if anyone out there has a set kicking around.

Cheers!

Anyone else ever been more happy than upset to get laid off? *lol* I figured I would have most of the last month to do odd jobs and get ahead on the bike project, but instead wound up finding some work for a few weeks, and doing 12 hour shifts outdoors in the lovely Canadian winter. Nice to have work, and not be completely broke during the holiday, but there are points when I wondered why I didn't just take the EI, sit inside drinking hot chocolate and work on the bike for three weeks..... Well, damn work ethic I suppose. Ah well. Anyway, there has been some progress nonetheless!

Woo! Goodies!





Some odds and ends from Z1, and CWS in Ohio. SS Rear brake lines, some new wiring goodies, and an assortment of grommets, seals and other bits which were either really grotty and beyond restoration of just fell apart when removed.

The big one tho...







Frame and swingy back from the powdercoaters. And what a nice job they did as well! Very professional, and a very reasonable price as well. I am going to bring a few more things in to get done as well, now that I've seen what their work is like. Bringing the whole things in all prepped made a huge difference in price, and I figure the battery box, engine mounts, case protectors and triple tree arms would look nice with matched colour, so I will see about getting those done as well.

All in all, I am once again (mainly) unemployed, and strangely happy about it at the moment. :woohoo:

Jon

I was also never really happy about having a couple of dents in my manifold, but since the were from the PO, and right where the pipes take a bend around the front of the frame, I didn't really figure I could do much about them.



Okay, so to be fair, I really can't personally do much about it, but I can pay someone to cut out the old pipe and weld in a nice piece of replacement pipe to match. Since I haven't any gear to do it myself, this is one of the jobs that will get shopped out. Anyway, I can build a jig to hold all the pipes in the right places tho. I figure saving $50 on the job by sacrificing a peice of 2x4 and 20 minutes of my time is worth it no?






Hope this works out well. I don't know how to weld anyway, and I figure welding thin wall pipes is not the place to learn! I will post up how that one turns out as well.

Cheers all!

look for a motocross pipe repair place. they can usually pop those dents out with a torch and air pressure. I had an old kerker that was pretty banged up repaired for $60

That would certainly be an option worth pursuing. I had figured they were just a bit too far gone, but it couldn't hurt to make a few calls and see if anyone reckons they can do the fix. Looks like I have some research to do...

Thanks for the tip!

Well, DoctoRot,

Thanks for the advice. Couldn't find a place locally that specialized in Motocross, but there is a custom exhaust business not too far from where I live, and they were able to pull the dent with a torch and slide hammer, or at least something like that. Pipes look great, and at least should have dealt with any potential exhaust gas flow restrictions. The exhaust system is indeed a Kerker like you had, and I was pretty happy to be able to just pay to get it fixed rather that find a new system. (I looked around at one point, and they were in the $600+ neighbourhood! :ohmy: ) While it was a little more than $60 to get this fix, it really wasn't that bad, and the manifold looks a whole lot better now. Cheers!
(As always, I will post some photos soon, I just have to get through the next most pressing thing.... the valve spring/shim swap.)

Jon

Ooookay,

So this is another one of the big parts in the rebuild, which of course has all the usual attached questions. Finally tore into the engine proper, with the intention of swapping in APE valve springs and changing out the valve guide seals. The job actually went quite well, and without any major hitches, so I am more than happy with the progress on that front. However, it also lead to what seems to be the inevitable series of questions which this project has thus far come across.... That is to say, I need to swap out a couple of valve shims to get clearances right, and am curious about the condition of the combustion chamber, and what you folks out there with far more experience that I have think.

So, to start: all intake valve clearance were 0.15mm. I am more than happy with this and don't intent to mess with them at all. I may be just a hair larger than the 'perfect tune', but the point had been made a couple of time in the past (from searching old posts, and also from 650info that clearances shrink over time, they don't grow. Good enough. Exhaust valve clearance however, are a slightly different story.

Ex #1 - almost nil, less than 0.05mm (shim @260)
Ex#2 - 0.15 - more or less perfect
Ex#3 - ~0.21 (shim at 245)
Ex#4 - ~0.21 (shim at 245)

Now, using the shim size calculator, it was a reasonably easy thing to figure out what to replace the shims with. No's 3 and 4 will get swapped out to 250s to tighten up the clearance there, and #2 will remain as is, since it is pretty much spot on. Now, #1 is a bit of a guess, since my smallest feeler guage was 0.05mm, and I couldn't get it to slide in. I don't know exactly how that came to pass since I checked valve clearance less than a few thousand K's ago, and I was at least within spec at the time, but there you have it. Far too tight, and would like to remedy that. I am going to assume for the moment that there is some tiny amount of clearance, and by moving back to a 250, it should get me in the vicinity of .10 or .11 measured once reassembled. Perhaps it would be smart to pick up extra shim at 255 in case that isn't enough. This is where I am asking for advice. Those shims swaps will give all exhaust valves a (calculated) clearance of between 0.14 and 0.16, which I personally thought wasn't too bad accounting for metal expansion with heat, and wear over time. I seem to recall that the common consensus was to leave exhaust valves a little on the loose side as they get hotter, and therefore are subject to greater thermal expansion. I Just hope that I don't swap in all these new shims and wind up with clearances which are all out of keeping with what the calculations seems to suggest.

Okay. That is post #1 for the evening, and kind of technical. So, feedback is appreciated, and I will try to get out tomorrow for some new shims. We will see how that goes. Next up: the ugly. :whistle:

Jon

And again..... This time with pictures.

So, without further ado....





This is the inside of the chambers, and condition of the top of the pistons.





Okay, so all in all, there is a fair bit of carbon, but for the most part it is not hardened and impossible to remove. In fact on a couple of the piston heads, it has every appearance of being very loosely attached, and could probably be removed with a Scotch brite pad, some solvent and a little time. Now, that being said, I have had some issues with burning a little oil on cold starts in the history of this bike, which I mainly thought might be remedied with new valve seals. I am a little vague on the history of this bike, but the PO did seems to have have taken good care of it, and there is evidence that someone has been through at least part of this motor before. it may be hard to make out, but there are pretty clear marks on the cylinder walls where it appears to have been rescored, and the tiny parts on the edges of the piston heads where there isn't some carbon, the surface appears to be quite bright and shiny. Right, now I know that this isn't some sign that all is good, and leave all as is, however, I am making the big leap here and figuring that perhaps much of the fouling is due to some small amount of oil creep after long periods of standing, and perhaps old valve seals.

I would like very much not to have to pull the jugs and replace piston rings etc.... (bike is just over 30k kilometers, so I somehow don't think overall wear is the issue, but I am receptive to varying opinions!) Also, bearing in mind that compression was good (tho I failed to write down the numbers when I checked it! :pinch: )

So, as it stands, I kind of figure just a good cleaning up of the current deposits and a thorough check that all valves are sealing on reassembly is most of what is required. (On top of a very thorough check to ensure that timing is correct before starting it all up again!) I would really like some advice tho, while I am at this stage of dissasembly. I'd rather spend more time and be thorough, than slap it all back together and miss something in the process.



For what it is worth, this was the single worst valve of all of 'em. Ex #2. Strange, as it was the only one with clearance within spec.... any thoughts are appreciated.

Thanks very much in advance to all!

Jon

Jon,
The KZ650c has always been one of my favorite Kawasaki's and it looks like you have a nice one!
Have you given any thought to using a set of zr750 carbs. They are a few sets on ebay, there are jet kits
for them and they work very well. They would also be easier to find parts for.
Just an idea.

Hey 80B4,

I did realize that was an option by way of swapping out to a different model of carb entirely. I won't rule it out, but for the moment I found a set of 26mm Mikunis. If that doesn't remain a good option for whatever reason, I will take a closer look at the 750 carbs.

I am more familiar with the slide carb type, but it might not hurt to get a little review on the operation and tuning of the CV carbs as well!

Cheers!
Jon