running out of ideas! kz550a

Tyrell Corp wrote: 135- 140 psi hot compression seems ok to me - most compression testers aren't that accurate. Try a wet test to narrow down the problem further. The zx550 models have 280 degree cams, the z550 models are IIRC 248 degrees: the wilder the cam the lower the cranking pressure . I don't think this 'low' compression is your problem anyway, more likely being chronically over rich.

Firstly I'd equalise the main jets at 105, . The big suzukis have differing inner cylinder fuelling to compensate for the heat differences but i'm not sure kawasaki did it onany of the kz models.. Just one step to 107.5 is enough to make it unrideable at WOT. Tune top to bottom, ie get your WOT main jet set, then needle etc

Your coils should be at B+ voltage, low coil voltage causes misfires and the ' relay mod' is just folklore and witchcraft. Also I'd use new HT leads and caps all round.

Even if the motor is a bit tired it should still pull hard to the redline. A bit more explaination of your symptoms might help too.

loudhvx wrote:

Jeff86 wrote: Interesting my Manual say 130 is min before service and 150 is stock. Ill check another manual as well. if my cam timming is not set correctly would this alter my compression. I cant see it being the rings, they are new, and the jugs were in great shape. plus i dont see or smell burning oil. and the oil level has not dropped. is there somewhere on here that explains a leak down test? or how to do it?

I have several manuals in my signature. For reference, you should grab all of them. The 155psi limit comes from the FSM which starts out with the Kz500. I see no mention in the supplement for the later models, including the gpz550 (which has higher compression), so I assume they meant that limit for the entire 400/500/550 family. The Clymer manual states 125 psi as the limit, likewise, no mention in the supplement for the later years. In my epxerience measuring mostly Gpz Kz550's, the compression measured on many motors, over many years, using many different gauges, was always around 180 psi, for stock motors. I only have one motor that may have been shaved as it gets near 200 psi. To me, even 150 sounds very low, and so 120 sounds very low. The larger motors (650/700/750 family and 900/1000 family) do seem to have lower compression pressures based on seeing what's been posted on Kzrider. They tend to run even down around 100 psi. I have some worn engines, and they are still up around 180 psi.

I believe incorrect cam timing would affect compression test numbers, but I've never played with that. You may have already seen the cam-timing notes in my signature, but if not, you can use it to compare what yours is set at.

You basically connect an air compressor hose to a spark plug fitting and inject air into the cylinder through the spark plug hole when at TDC of the power stroke. You can buy the fitting, or you can bust up a spark plug and weld (braze etc) a pipe to it. That's what I did.

You will hear hissing if it's leaking. It may hiss through the intake, or exhaust, or through the crankcase. Where you hear it will tell you where it's leaking.

Have you used other compression gauges before? Some are not made right. There needs to be a check valve at the very tip that goes into the cylinder. Sometimes they put the check valve far away from the tip. This results in very low numbers. The gauge must hold pressure across several compression strokes because the added volume of the test equipment requires more air to be pumped. Once the test equipment is up to a constant pressure, that's the most pressure the motor can build for the test. Putting the check valve further in lets air dump out of the test equipment, so each pulse never reaches full pressure. It's almost as if they didn't even understand what they were making, or what it was supposed to do. China.

Jeff86 wrote: ... but how can it be this rich with the 30 pilots and needle on the third? the mains are not doing anything at start or idle, correct?

Needle on third clip is a lot richer than stock. But with pods, I would not expect it to be too rich. Correct, the main has negligible affect at idle, but on start, it depends on how you start. On mine, when I know I need more fuel at startup, I give it a lot of throttle, so the mains do affect it. There may even be some affect if you start with no throttle, but I doubt it. Starting is too chaotic to really predict, but at idle, the needle does have some affect.

Where are your screws set at?
they are at 1.5 turns out.

Jeff86 wrote: ...when I got the bike the previous owner had 96's. but the bike didnt run from the beginning. so i never tried them and had always assumed i needed bigger based on web searches.

The 96's are probably the stock Gpz 1981 Kz550D1 jets. I assume you would probably need to go bigger than 96, but I would try them as is first. With a quiet exhaust, they might work.

Just to reiterate, when checking the mains, you need to check this first:

It is possible for the throttle to open past full-open. Beyond that, you only add more fuel, but no more air. The Tk22 site shows how to tell where the slide is at. Actually, with pods, you can just take one off and see if the slide goes higher than the ceiling of the carb throat.

This being set beyond full open will sometimes result in the sensation that the bike is speeding up as you just start to close the throttle from WOT.
Great i will check this out tonight

Jeff86 wrote: They had told me that with pods at idle and roll of that you actually get less air then the stock air box, because the air is not being funneled or controlled so the suction or vacuum is lower.

In my experience, jetting several 550's with TK22's and pods, this does not hold up. With pods, it always ends up leaner than with the airbox, under all conditions that I've checked.

I wonder, though. Does having significantly lower compression mean you need less jetting since the engine is not breathing as well as it should? I recall my friend having a really high-mile, very low compression, Kz650, and it kept fouling plugs. It was originally was jetted with pods and supposedly ran good. But years and many miles later, it was fouling plugs pretty badly. I reduced the jetting a lot to dry up the plugs, but it still wasn't right. My buddy sold it before I could really spend any time on the jetting. We replaced the entire ignition system and did a valve clearance check. The compression being very low was all I could find wrong. I think it was somewhere around 120 psi as well.
This makes sense to me, I can see how lower compression would alter the jetting a lot.

Jeff86 wrote:
which brings me to another point. when trying to synch the carbs, we could barely get the gauges to move. 2-4 moved up slightly, i forget the number but it was low. #1 would not move no matter what we did.

That's not good. With a fast idle, on the gpz, I get about 20 cm of mercury with pods.
It's a lot of reading, but here are my notes on manometers in general.
home.comcast.net/~loudgpz/GPZweb/Manomet.../ManometerNotes.html
This you tube link shows my manometer in use on the gpz so you can see how it looks with throttle blipping etc. (It was a really cold day, so I had the idle way up to get off the choke.

as much as I dont want to read it all I will. this motorcycle stuff is heavy reading all the time! lol

Jeff86 wrote: I will order some stock jets and go from there. I have the drill set to go bigger if need be. sadly i cant make this jet kit i bought smaller! dang

Jeff86 wrote: do you know if the Z1 Keihin main jets are good to use on this bike?
www.z1enterprises.com/ItemDetails.aspx?i...00&item=SIKHM-110100

I would rather just order a bunch of main and keep trying them until i figure it out.

Jeff86 wrote: ...how can it be this rich with the 30 pilots and needle on the third? the mains are not doing anything at start or idle, correct?

Jeff86 wrote: You said "Dyna S coils". The Dyna S is an ignition kit, but does not include coils. Did you mean Dyna coils? Or did you mean a Dyna S ignition with Dyna coils? Since I see you mentioned points, I assume you only meant the coils. 3 ohm coils are a little low for points. Their life will be shortened by some amount, but should still work for the time being.
Sorry yes I meant to say dyna coils. These are the ones recommended by Z1

What do you mean the timing on the #4 exhaust valve is almost out of spec. You can't independently time each valve. Did you mean lash gap? As long as it's within spec, don't worry.
Yes the valve clearance is what i meant

Since you already have new coils, then I would also recommend an electronic ignition from a later 550/650/750. Or you can use a Dyna S ignition, but since your bike is a single phase charging system, the Dyna S might tax it a bit. The factory system would work well. But I don't think this, alone, is your problem.
I will try and track one down, thanks

The battery should get over 14v and stay there once the RPM's are above 2000 or so. If not, you may want to look into the charging system.
I have not checked it while running. I will do this and report back

The compressions sounds too low. Kawasaki says 155psi is the bottom of the usable range. I wouldn't expect it to run too good that low. But that may improve some with some break-in. I assume you know to do the test hot with no choke and the throttle wide open. A leak down test would be good to see where it's leaking. I think this may be your biggest problem at the moment, if those numbers are in fact accurate.
Interesting my Manual say 130 is min before service and 150 is stock. Ill check another manual as well. if my cam timming is not set correctly would this alter my compression. I cant see it being the rings, they are new, and the jugs were in great shape. plus i dont see or smell burning oil. and the oil level has not dropped. is there somewhere on here that explains a leak down test? or how to do it?

Your AFR numbers show it's too rich (as you said). And if a KZ550 starts cold with no choke on a cold day, it's definitely too rich. Even in summer, on a bike that is slightly rich, I still have to use some amount of choke on a cold start.
agreed. but how can it be this rich with the 30 pilots and needle on the third? the mains are not doing anything at start or idle, correct?

On a Gpz, with pods, and more open 4-into-1, the largest main I use is a 103. That means a standard (Kz550A or Kz550C) would probably max out at 100 or 102. Maybe with a totally open pipe it would be in the 105 range. Sometimes people use a larger main to mask the effects of using a stock pilot or stock (fixed) needle, So maybe that is why they recommend such a large main, but in your case, it's just too big.
Interesting, when I got the bike the previous owner had 96's. but the bike didnt run from the beginning. so i never tried them and had always assumed i needed bigger based on web searches.

WOT, however, may not give a true indication of the jetting. It is possible for the throttle to open past full-open. Beyond that, you only add more fuel, but no more air. The Tk22 site shows how to tell where the slide is at. Actually, with pods, you can just take one off and see if the slide goes higher than the ceiling of the carb throat. The afr should rarely go richer than 9 or 10 under normal, or even spirited riding, and then only when you've opened the throttle a little too fast. If you go richer to where it's misfiring, the wideband will usually show really erratic numbers. When there is a misfire, and no burn, you have a lot of raw oxygen in the exhaust, so it will often register super lean, even though it's super rich. Then when it fires, it will register super rich.

This brings us to the jet kit. I don't have any experience with that kit. What type of jets does it come with? On the tk site, I have photos posted of the various jets I've come across, for comparison. The pilot #30 is puzzling. I wonder how they got that. There has never been a Kz500/550/400-4 that came with any pilot other than a #32. All of the rebuild kits only come with #32. No other pilot will substitute, so it would be interesting to know where that #30 came from.
They had told me that with pods at idle and roll of that you actually get less air then the stock air box, because the air is not being funneled or controlled so the suction or vacuum is lower. which brings me to another point. when trying to synch the carbs, we could barely get the gauges to move. 2-4 moved up slightly, i forget the number but it was low. #1 would not move no matter what we did.

I assume it came with adjustable versions of the stock needles, as they are the only ones I know of that have 5 grooves (the Dynojet needles have 6). 3rd from the top, as you have it, is a good starting point for the needles.
correct

I have not seen much reason to run richer jets on 2 and 3 (compared to 1 and 4) on the KZ550's. They seem to do well with all four the same. If the two inner cylinders run hotter, they will already be running richer when hot.
Agreed but i was desperate to try anything and thats why I ordered a kit from them. www.6sigmajetkit.com/

I guess the first step is to figure out the compression issue.

Next would be a voltage check on the coils while revving. It should be closer to 14v. (But I don't think this is your problem.)

Next, I would go to 100 mains, and set the air screws using the lean drop method. The idle, when warm, should end up around 11.5 to 12.5 on the AFR depending on outside temp. If the air screws are turned out less than 1/2 turn, you will probably want to up the pilot jet to #32 (stock). Usually, with pods, as long as there are no vac leaks, I find the pilots have to drilled out to at least 34, sometimes 37.