Kz550 1980

Just got an early model kz550 with slide carbs. I've heard these slide carbs are notorious for erm, being notorious I presume.
Anyway, many moons ago I had an 81 z550d1 with the constant depression carbs on which functioned faultlessly.

Could I simply swap the slide carbs for the later constant depression type or is it more complicated than that? Any advice appreciated.

I don't know where you heard the slide cabs are a problem :blink: I wouldn't trade mine for any others, and I certainly wouldn't trade mine for CV carbs whose diaphragms can self destruct and can be difficult to find and expensive.

How about this idea - before going in and trying to modify and swap a bunch of stuff on the bike because somebody's brother-in-law knew a guy who thought it was a good idea, why not actually RIDE the bike and see how it performs? These bikes all ran well off the showroom floor, so if you clean it up, perform the normal maintenance items, and fix anything a previous owner broke you may be surprised to learn you have a nice bike. Ed

Thanks but that's no help really and quite patronising on the whole.
If anybody has any constructive advice......
The bike rides fine to begin with but five minutes out it begins to run very lumpy and retarded particularly at mid revs, so its coughing and spluttering when underway but will run at tickover.
After new plugs and leads, a pair of s/h coils (the ones on it were very wrong!),
this now led me to think it was fuel delivery.
The carbs have K&N filters on (which i don't like) so this could be another reason for poor running.
Now the point is, to put an original airbox back on may require carb adjustment (if they have been adjusted to accommodate the K&Ns that it.) so it may be easier to get a set of carbs with an airbox if (as per original question) they can go straight on.

I cant offer any advice on a carb replacement but often when the k&n style filters are installed instead of the factory air box, the carbs aren't rejetted. I would first start by checking the jet sizes in the TK-22's and comparing them with stock. It would be a lot cheaper and easier to buy an air box (and the correct jets if needed) than to buy completely new carbs. Unless you are planning on doing a major upgrade of some sort, the bike will run best with the stock setup

Some of your info is wrong. The 1981 KZ550D1 uses the same carbs as the 1980 KZ550 A and C models.
The TK22 carbs are notorious for being very easy to tune and relatively simple, mechanically.

The TK26 CV carbs did not show up until the 1982 KZ550 H1, F1, and M1 models.

And to answer the question, while anything can be done with enough money and work, no, the TK26 cv carbs will not simply swap onto the earlier motors. The bolt spacing on the intake manifolds are wider apart on the later motors, so they can't be bolted onto the earlier motors. And one can't move the bolts closer because they would then interfere with the larger diameter throat from the carbs.

Also, the later motors have larger intake ports to match the CV carbs (hence the wider bolt spacing). If you somehow made some adapter manifolds, the intake path would have to step down to a narrower size.

Also, the airbox for the later CV carbs does not fit the earlier style frame, so you would still have to use the K&N filters or some other non-stock filters, or you could try to modify the original airbox, but if you have that, then you could just put that on and use the TK22 carbs.

All of the available rebuild kits come with the stock jets for the non-gpz models. So a rebuild kit would guarantee you can restore the carbs to their factory jetting.

Your symptoms can be caused by several different issues, one of which is valve lash, so it would be best to start at the beginning since it's a new bike to you. Have you done a compression test, and checked the valve lash?
There is a link in my signature about dealing with the valve lash, which includes a warning about not installing the valve cover without releasing the cam-chain tension.
In addition to that, my signature contains links to multiple different manuals for the early KZ550 family of bikes. I recommend downloading all of them for reference.
There is also a link dedicated to the TK22 carbs.

Next would be to verify timing with a light, which would also show if there is some spark loss. Do you have an A model or C model? The A model came with points. If you have points what condition are they in?

Pictures of the carbs you currently have would help get them identified if you don't know for sure they are stock.

Changing the carbs will also have you changing the throttle and cables, so I agree with trying to get it to run as is before moving on.

firstly thanks for the informed responses.
Maybe my d1 was then in fact a later h or something, or had a later replacement engine as the carbs were definitely cv.
Anyway that's bye-the-bye now seeing that they won't fit my a1 without modifications, again thanks for that knowledge.

Compression is next on my list, the test gauge should arrive tomorrow! I'll post the results for your expert considerations.

I'll now check out your links loudhvx and thanks, any info on these bikes is well appreciated, as I will be delving much more into the nut-and-bolts in the coming months/years. My first zed was in my heady 20s so not much respect for the nuts-and-bolts side of the machines, besides, they were of-the -time in the 80s and were readily/cheaply repaired by all bike mechanics. I took mine to a local bike mechanic to which he informed me he didn't work on bikes that old! That bluntly informed me I would need more of a hand's on approach.

As for points, I went to check and shock horror they were not there! Tracing the wiring it came to a black box with Pirhana stamped on it. So it's had an electronic ignition fitted at some point. And presumably, (I hear you all gasp,) the plot will thicken.

I'll post a pic of them CoreyClough.

Here is the bike and the carbs

That's going to be a great looking bike. I don't know how you feel about the color, but I love it.

Those are definitely the TK22 carbs,

Looks like you have a few things to sort out, though.

After compression and lash, the next is ignition.
I am not familiar with the Pirhana, but there were a few dodgy aftermarket ignitions back then. That is high on the list for possible causes to the poor running after warm up. When it comes time to check the advance curve, a timing light will also help to show if the Pirhana is dropping sparks.
All of the KZ550's originally came with electronic ignition and 2.3 ohm coils except the first year A model (1980 A1), which came with points and 4 ohm coils, at least here in the U.S. I can see already, your A1 is slightly different from the U.S. version since you have dual front disks. It would be good to know what ohms your coils are in case you have to look for a new ignition.

After the ignition is completely sorted out, then move on to the carbs.
Obviously those filters have to go. You will likely also want to get the proper clamps for the engine side of the carbs. Also be aware, new rubber intake manifolds are available for your bike. Those will go a long way toward eliminating headaches caused by vacuum leaks.

I have gone back and forth with stock airboxes and individual pod filters for 20 years, and currently have both on different bikes. I really like the feel of the pods on the highway. The motor just seems to have more zing. For stop and go riding, and with a passenger, the airbox has a slight advantage. It just doesn't require as much attention to clutch and throttle to ride perfectly smoothly. The differences between the two are subtle, but noticeable. If you are likely to ride in the rain a lot, or at least get caught in the rain, you would probably want the airbox. But be warned, it is not a fun task removing and installing carbs with the airbox in place.

As far as pods go, I prefer the no-maintenance, disposable Emgo pods. They don't get oiled, so they don't cover your hand with goo every time you try to adjust something on the carbs, and they are very inexpensive. I've tried the K&N's and despite being re-useable, they do deteriorate, and cost a fortune, not to mention you have to buy a bunch of chemicals for them, which are not cheap either. I hated spending half a day washing, drying, and oiling the filters. The same goes for the UNI foam filters. But they started to crumble internally, so did not last as long as the K&N's.

In order for that bike to ever have run correctly with pod filters, the jetting must have been altered, so you will likely want rebuild kits if you get an airbox. But it would be best to check and see what you have. The TK22-s really only have three items to check for jetting: The main jet, the pilot jet, and the needle. In the U.S, we did not get adjustable needles, but you likely did. You can use Keihin small-head mains as a substitute for the mains. So that is two of the three items. The pilot jet is not available anywhere, except in the rebuild kits. If your pilots are original (and not drilled), then you can probably just order some main jets. However, there is a chance the pilots were drilled out, so it wouldn't hurt to get rebuild kits.

The TK22 site has details on the internal differences of the various brands of jets, and some info on drilling the jets.

One other thing... I notice you have an inline fuel filter. Lately, at least here in the U.S. where we get a lot of alcohol in the gas, some fuel filters designed for fuel-pumps have shown to stop flowing fuel after some time. These are usually a see-through, pleated-paper type filter. They will stop flowing even when perfectly clean. I think the glue in the filter starts to dissolve from the alcohol, and when it coats the paper, the paper stops flowing fuel. Switching to a scintered bronze/brass filter or metal-screen type filter eliminates this problem.

That's very interesting about the fuel filters. I'll replace it just to be on the safe side. I think it must have been fitted originally along with the inside of the fuel tank being sprayed. I suppose it's best to have a fuel filter anyhow.

I have just measured the coil Ohms and both coils are reading 2.8 (i'm presuming that the coils being still bolted to the frame would not affect this reading) I don't know what the correct Ohms should be for the replacement Pirhana ignition, or whether this matters. I can't find any mention of Pirhana electronic ignitions online.

I'll wait then to see the outcome of the compression test and we'll take it from there.

I've been a little busy over the last two weeks acquiring another steed to the stable. I finally managed to find a Gpz550d1, rode it home 300 miles yesterday, beautiful for a 32year old bike!

Anyway, back to the current issue, that's if anyone is still following my trials with the kz. results of compression test No.1 = 75psi No.2 = 70psi No.3 = 80psi No.4 = 105psi

now this threw me again as I was expecting one cylinder to be lower compression. Firstly are these readings within the accepted parameters.

Jape wrote: ... results of compression test No.1 = 75psi No.2 = 70psi No.3 = 80psi No.4 = 105psi

now this threw me again as I was expecting one cylinder to be lower compression. Firstly are these readings within the accepted parameters.

Those numbers are not acceptable, If you haven't downloaded all of the manuals in my signature, you probably should.

Here's the compression test section from the white base manual:



(Save the image to see it full size.)

Hmm, the manual doesn't say this, but you need to make sure each plug wire is grounded to avoid damaging the ignition system. It can be damaged instantly if there is no path for the spark to discharge. You can also just disconnect one of the two small wires from each coil.

How did you do the test? Choke and throttle locked fully wide open?
Being that low, I wouldn't expect that motor to be very easy to start or run properly at all.
What gauge are you using for the test? Does it have a check valve right at the very tip extending into the spark plug hole, which can hold pressure indefinitely? Does the gauge hold the reading until you release the pressure? Some cheaper designs put the check valve in the wrong place, or use none at all, as if they don't even understand how a compression gauge works.