Wiseco 615 Big Bore Kit

To me, it sounds like a slack timing chain.
I can't comment on tensioner compatibility between GPz and ZR models, as I don't have a ZR tensioner or head  to compare...

​​​​​​ Correct tensioner adjustment range, on KZ and GPz 550 should be as shown below:  excerpt from the Kawasaki manual. 
However, this may not be correct for a ZR tensioner fitted to a GPz head. 



I can't be sure, but comparing pictures of the GPz head and ZR head, it "seems" that the tensioner mounting face on the GPz head is further out, resulting in the ZR tensioner being too short...

ZR Head
​​​​

GPz Head
 

If it were mine, I would just fit a GPz tensioner, alternately, a manual tensioner...

H.

Did you remember to set the cam chain tensioner AFTER installing the valve cover?  Failing to do this will result in an over tensioned cam chain, possibly leading to guide failure.

Wow, so many helpful responses and great information. I posted that video some days ago, and actually meant to chime back in to say that I've already got the problem fixed! Mostly anyway. I re-checked the cam chain timing, which was spot-on, then readjusted the cam chain tensioner (it's a manual type off eBay), and the noise went away entirely. I was still having what seemed like a spark issue, so I swapped in some other spark plugs (more on that later), and the bike runs. I rode it to work and back on Saturday, which is only about four miles round trip, but still.

I mis-spoke when I said "bored and sleeved" that was just n00b ignorance, because this is the first time I've ever messed with anything like this. So to clarify, yes, I bought the '81 GPZ550 cylinder block already bored, but it was not re-sleeved. I have to admit that I played it pretty fast and loose with it, just sort of trusting that everything was going to work. There was no indication that it mattered which piston went in which bore, so other than checking piston ring gap, I just sort of went for it.

So it is running now, and honestly I think sounds pretty good, though I am far from an expert. I have noticed what sounds like some knocking at idle, and I think there is some carb balancing needed. I don't know if it might also be running too rich or too lean, and which jets might need to be swapped to fix that. Again, this is the "fine tuning" part of things that I am just too inexperienced to know. I happen to have a Factory Pro Stage 1 jetting kit that came with this bike. The previous owner had intended to run pod filters, but I put the stock airbox back on. How do we feel about the Factory Pro stuff? If I do need to re-jet the bike now, should I go ahead and start with that since I already have it? Or should I source the genuine Keihin jets? 

One of my coworkers at my day job used to rebuild Porsche 911 engines professionally and he mentioned that higher compression pistons require colder spark plugs. Does anyone know anything about this? The stock plug for the ZR550 is the NGK D9EA, but when I got this bike it had D8EA plugs installed. In doing the whole rebuild I swapped back in some old D9EA's that I had from my other bike, which I had cleaned. No real surprise that they weren't necessarily working right. So I put the D8EA's back in and that's when the bike really started to sound like it was running right. Can anyone comment on that? Is it true that I should be using a colder sparking plug, and is the D8EA a better choice than the D9EA? 

It makes complete sense as higher compression equals higher combustion temperatures

Oh, and one more thing. I found this part  listed as a replacement for the regular cam chain tensioner, and noticed that it looks like a simple spring-loaded replacement, which at least to me makes a lot of sense. It's less expensive, and potentially less faulty than the stock tensioner, and wouldn't require periodic adjustment like a manual tensioner. Does anyone have any experience with these? 

Glad it's running quietly now!

And, congratulations are in order... You've successfully competed a fairly complex job!

Jetting is a "process", and you gotta start somewhere... so use what you got.. 

My 1981 GPz 550 D1, with standard airbox and a KerKer 4 into 1, has 102 main jets and stock pilots. But I live up at 5800 ft. A seasoned drag racer advised me that every 1000 ft of altitude typically requires a 1 jet size reduction, so If I was at sea level, 107 - 108 would be good.

I note that the tensioner you refer too, from CMS is for a ZR 550 head, and not for the GPz...
It's not that simple, it has a " ratchet and pawl" mechanism that makes it "self adjusting" pretty much the same as a stock tensioner.

Anyhow, that manual tensioner you have installed will serve you well... If you adhere to Kawasaki recommended service intervals, and just listen... (you already know what " too loose " sounds like!   )

As for the spark plugs, D8EA's will be fine.

H.



​​

I wouldn't change the plugs unless you have a problem with the D9EA's.  If they foul and the electrode looks all burnt and melted, then something cooler is in order.  Remember, colder plugs doesn't make the combustion run colder.  It's just a plug thing, to allow it to live with the higher temps.

The manual chain tensioner you have is far more reliable than any auto version you can find. 
Factory Pro is the best jet kits you can find for the zr550. A member from Zerphyr-Zone (and maybe here?) who passed away many years ago had worked for the company and they used his bike to develop and dyno test the Zephyr jet kits. The best part is they do not rely on drilling a hole in the vacuum slide, like the other kits. (Thus permanently screwing up the tune of the carbs if you ever wanted to go back to stock) 
I currently have the stage 1 kit in my zr550 with the air box but I used to run the stage 3 when I had pods. 
I also currently have the stage 3 kit on my 750 with pod filters. 
I have always run stock temp plugs on my zr550 (with zx550 higher compression pistons) and in my 750 that is bored out to 810. 
Lastly, if you sync your carbs, most if not all of the primary chain and clutch basket clunking will disappear. 

Congrats on the install! That two zr550s with 615 kits in the past few months (including mine)

 I also just dropped a 615cc kit into a GPZ550, still fighting carb issues though.  (I’m) just about to the point of binning the stockers and buying a set of stupid expensive 26mm CR’s for it.   I’ve done a lot of improvements to it and I think it’s worth the better fueling and ease of tuning.  I have late model cams, ported and polished head, valve job, Kerker Pipe, new electrics, 615cc kit.   I just don’t think the stock 22mm carbs can keep up and are choking the flow.  

You've certainly done a lot more with yours than I have with mine. I'm still running everything stock, besides the big bore kit. I'm just not an expert, so I can't say that it's running 100% optimal, but it does seem like it's working fine for me. 

577nitro wrote:

 I also just dropped a 615cc kit into a GPZ550, still fighting carb issues though.  (I’m) just about to the point of binning the stockers and buying a set of stupid expensive 26mm CR’s for it.   I’ve done a lot of improvements to it and I think it’s worth the better fueling and ease of tuning.  I have late model cams, ported and polished head, valve job, Kerker Pipe, new electrics, 615cc kit.   I just don’t think the stock 22mm carbs can keep up and are choking the flow.  a

Are you using pods or the stock the airbox?  Corey had good success using CV32 carbs with the 615 kit and pods - 

kzrider.com/forum/2-engine/442737-gpz550...arbs-615cc-dyno-tune

I'm still trying to dial my jetting in on my zr550 with the 615 kit and CV30 carbs.  Mostly it's running OK but I'm struggling to get a strong idle.