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No eBay APP ID and/or Cert ID defined in Kunena configurationYou may have just got a dud set of rings for that piston, why not just contact cruzinimage and let him know, I'm aware of quite a few people using these kits in other bikes without trouble, so maybe you were just unlucky and got a dud set. Weisco 810's would possible fit too... Off topic, I was reading a couple of pages back about the Dorimi collection stuff, I've been aware of these kits for some time now, anyway, a friend of mine in the UK dropped me this link for a 750 Zephyr body kit, the price is great and lower than the other kits {same kits} listed in their ebay shop.... Kinda wish I'd bought a zephyr now...

Daftrusty wrote: Well, I took of the exhaust and #3 exhaust port had a pool of oil sitting in it. So I removed the entire top end and was able to verify that the oil control ring had jumped. I will try tomorrow to remove the rings and inspect them and get pictures for documentation. I would also like to measure the 69mm piston rings and see how close in size they are to the stock ones and then look into the possibility of replacing them with ones from another manufacturer.

Why can't you just reuse those rings? If the oil control expander overlapped can't you just bend the tangs up some or get a new expander alone and reuse everything else? Your compression was good so no worry there. The only issue was that one ring.

After removing the rings to get a closer look, it turns out not only did the expander ring jump, but part of the little tang had broken off.
Initially I had issues where the ends of the expander ring met where one end was not cut properly and it had sort of an "S" shape and it would not meet up flush with the other end. So I put a file in my vise an proceeded to very carefully file of the end flush. Apparently I was not gentle enough and must be the reason it broke off. So this situation was caused by the ring being defective and me not fixing it properly.
I gave up on the up on the idea of using a different manufacturer of rings as the Cruzinimage pistons use 1mm for the top ring and 1.5mm for the second and 2.5 for the oil scrapers. I could not find another aftermarket set of rings with that combination of ring sizes and in 69mm, so I just bit the bullet and ordered 5 sets Cruzinimage rings so I have enough to replace my current ring issue and have spares for a later date.

Broken ring



How its supposed to look




What the OEM one looks like




While I had everything apart I took the opportunity to fix an issue I had with the APE head studs I am using. When I went to install the head I found that the four studs between the 1&2 and 3&4 cylinders were about 5mm to short. I had to forgo the use of the washers to get enough threads to safely torque down the nuts. I found this strange because I used a thread chase and not a tap, to clean out the threads. I was aware that using a tap could lead to this issue of the studs screwing down to far into the case, so the studs must have be manufactured to short. So after an hour of measuring and scratching my head I came up with the solution of using two 5/16 ball bearings in the hole to prevent the stud from screwing down to far into the case. (Giving me 6mm more threads up top yet giving it enough threads in the case.)
With that sorted I now wait for my new parts to arrive.

Are you going to replace all the rings at this point or just that one hole? Seems excessive to replace rings that were working well, that one damaged ring excepted.

I'm just going to replace the one oil control ring on #3. I just bought the extra sets of rings for (hopefully) years down the road when they are no longer available.
Because I needed another head gasket, (because I removed all of the pistons to closely inspect them all.) new wrist pin clips and 4 extra sets of rings, it was more cost effective to buy a whole new piston kit and a 5th ring set than it was to buy all of it seperetly. So I will have a spare set of pistons now.

When you mentioned the heavy smoke I kinda thought you'd find a problem with the spreader. I had something similar happen on a Wiseco piston that I used in race single that I was building. The spreader seemed too long, and kept popping the scrapers out during install. Eventually I intentionally clipped a couple MM off the end, and it went in smoothly. It was a race engine, so a little smoke wouldnt be a problem. Well, it pretty much turned my engine into an oil pump, and could probably have pumped the crankcase dry in 10 minutes or so. Needless to say, I didn't make the race the following day.

Those Cruzinimage oil ring expanders don't look like the ends are designed / formed properly....it looks like the angle the two ends butt against each other is not square enough, inviting a problem with overlap.

I hope you have better fortune in putting the pistons in this time....and quite happy that the cylinder bore didn't get scored by the defective ring....

I had only one spot of trouble putting in rings before - I managed to snap a 2nd ring once on a Honda while heavy hand coaxing the cylinder into place. That also nearly emptied the sump of oil in just a few seconds - better than an oil pump would have....unfortunately it also damaged the freshly re-bored cylinder...what a waste

So I finally have my engine back together with a new oil ring expander for #3 piston. Thankfully it runs just as it should and now with no oil smoke! So I can finally post a video of it running to show my progress.
I have been riding around the subdivision because I have no insurance and expired plates, but I snuck it out on the rural road next to my neighborhood just to see how it shifts and to check my carb jetting. It has surpassed my expectations so far. It shifts through all six gears like butter and doesn't sputter or bog at any point on acceleration. It does seem to stutter very very subtly when cruising at 70mph. But there was a 25mph wind blowing the whole day I did my road test, so it could have been that. So before I make and carb adjustments I will need to get more miles on it.



Now I have the winter to reposition my exhaust into a more aesthetic spot. As it is now, it is designed to bolt up to the pillion rear support and because I no longer have that, the megaphone points straight backwards in a odd way. Not to mention my support bracket for it is about 20" long. So I "intend" to come up with a mid-pipe to ad more upsweep to the megaphone like the vintage race bikes exhausts.

The next issue is that my Zephyr 750 carbs I got on ebay had looked to be used as a hammer at one point. I thought that the damage was limited to the cracked float bowl and caved in diaphragm lid. But after several heat cycles on the bike, I noticed that there is a long fracture in the intake side throat of the carb as well. ( I of course only noticed this just as I was finished syncing the carbs, so It means I get to do that all over again.) So I have a set of cvk32's from a zx600c on the way to replace the Zephyr ones. I tried to find a replacement carb body to replace the cracked one, but I could find every one but the one I needed.
I cannibalized my spare set of zr550 cvk30's for parts so I will end up with a complete set of 32's and 30's when I have everything sorted anyways.

The speedo is +5mph just like the one on my Zephyr. Its because the Bridgestone tires are smaller in circumference than the stock Bridgestone's of the exact same size. So when I was at 4000rpm's I should have been going 65 mph but my speedo was at a optimistic 70mph. I knew I should have bought the slightly wider and taller Battlax tire instead of the stock size. Fudge!

My kick stand is so short that it looks like the bike has fallen over. So its off to the salvage yard to find a longer replacement.

And of course paint. I simply cannot afford to have a quality job done at this point, so it looks like I am stuck with primer for the foreseeable future. Unless some one wants my basement of gpz550, zr550 and kz750 parts in exchange for a paint job?

such a killer bike!!

So, I have a quick question That's somewhat related... I have seen several videos of rebuilt engines that have a moderately high frequency sound that increases with rpm. Watching the video, it seems to be emitting from inside the engine. Is this a cam chain tensioner?

I have a kz700 and have never heard this sound. I recently switched over to a manual tensioner which quieted down engine noise by a considerable amount. While at idle and riding, I can only hear my primary drive chain, carbs (with pods, which I believe are louder than the stock box) and my exhaust. Is this an indication of something lot being adjusted correctly or parts worn out?

Again, great build! Totally inspired me to do a transmission swap this winter.

I know exactly the sound you are referring to. I would have been scared of this noise if I hadn't also heard dozens of kawasaki's make this same noise in videos. The supercharger whine on mine disappears as soon as the engine warms up.
It is not the cam chain tensioner. I am using a manual adjustment style and I am 99% confident it is adjusted correctly. (Finger snug, then back it of a 1/6th of a turn.)
I'm pretty sure it is the straight cut primary gears at the clutch hub and secondary shaft. Both my clutch and secondary shaft are from different bikes, so the straight cut gears are making noise as they "get to know each other" so to speak.
I don't believe it is the transmission as it whines in neutral and when in gear.

Also, thanks for the positive comments!

Awesome build. The engine sounds great in the video.

Straight cut gears make that characteristic whine noise. That's just how they are. KZ bikes are famous for it.

Thanks! That makes a lot of sense.