gpz 550 cams in a kz550 or zr550?

Be interesting to see that, Maybe a few runs with Air/fuel analysis and try altering the ignition timing. If you hear it knocking back off.

Thinking more on this, we know for certain the ZR head and block are different (from the outside at least) so even if the crank, hyvoid chain and timing gears were all the same part number, across the zx and zr parts list, it wouldn't guarantee correct valve timing if there any slight differences in block or head dimensions. Just on a skimmed head and the EX cam mark is out of alignment.

Why did kawasaki junk the zx head and bother to make another head and block for the dismally boring GT550 shaft and retro detuned zephyr? emmissions? tooling wearing out? styling? The later zx 'bathtub' head had a different valve angle... a lot of assumed unknowns here.

Regarding valve interference, I did a thread here a while ago with a big valve gpz head and TTS cams, graphing the valve to valve clearance 20 degrees before and after TDC on the overlap. Valve interference isn't a problem, in this case. Danger was piston to valve contact.

valve interference on overlap -pics gone awol but i graphed it out on paper

www.kzrider.com/forum/2-engine/599776-redline

if she's knocking...

kzrider.com/forum/2-engine/599063-thar-s...lows-tyrell-s-gpz550

I personally know that valve interferance is not an issue in the zr550 head with the ZX cams.
I have been running ZX550 cams AND sprockets (and pistons) in my stock un-decked Zephyr 550 head for years.
I have had both a zx550 head and my zephyr head on the same bench at the same time and never noticed any differences, beyond the
outside cosmetics. The combustions chambers, intake and exhaust runners, cam caps...etc all "look" identical.
At the time the only difference I remember was the zr550 valve springs were longer than the zx550 ones. Partzilla's cross reference tool seems very ambiguous about this difference. It shows the same 49078-1001 & 49078-1002 part # for all the 550 (and some kz750's) springs across the years, but the "also used on" list does never mentions the zx550 or Zephyrs. Somewhere I have a giant bag full of gpz and Zephyr valve springs. Maybe I can find that bag and get some comparison pictures. Or maybe I hallucinated the whole thing.

Zr550 head at the time of swapping over to the ZX550 cams and pistons.

Gentlemen, we have data!

Short version - the butt dyno didn't lie, lost a little on the bottom, gained a few ponies on top (up 3.5 hp to 55hp at the rear wheel!). Running rich up top which could explain the mileage issue. I received various recommendations from Raul and Marc at Factory Pro/Wheelsmith Racing for what to try next, which I'll discuss in a bit. But first - the charts!

ZX CAMS IN RED, STOCK CAMS IN BLUE



ZR550 DETAILS


ZX550 DETAILS

So Raul, who has been working at Wheelsmith Racing (Factory Pro's workshop) forever, was the one who did the dyno for me. His advice was simple - he said my bike is running rich up high and lean down low, and suggested I drop the main jet 2 sizes and go one up on the pilot. He also said he knows more about carbureted bikes than Marc Salvisberg (Mr. Factory Pro), though he conceded Marc was better with fuel injected bikes. He said I should listen to him and not Marc.

Marc's advice was to lower the floats 1mm and lower the main jet 1 size. He didn't think he had enough info to recommend what to do on the pilot, but suggested I adjust the mixture screws on the carbs using the lean drop method on each individual carb. Specifically, he said for each carb, close the mixture screw until the engine stumbles, then back it out until rpms increase to their max. Then lower the idle screw until the bike is barely idling and repeat the process. Then adjust the idle screw to whatever final idle I want. Interesting. He also said that I should get a slotted sprocket and advance the intake 2-4 degrees, and that this would put some of the power down lower where I can use it. Those 4 extra ponies the zx cams bought me are waaay up high in the rev range.

Seems like those two have a friendly little rivalry going. Not sure which way to go...

By the way, this is an engine with almost 50K miles. I really couldn't be more pleased with how it's holding up, and performing after a few mods.

No offence to you, but I see they didn’t run the Dyno at a high enough to show peak up. Where the red ends, it is still climbing. Bet it makes more on top at a little higher.

Glad you got to compare, and are happy with your results. I’d see if you can send them your carb settings to add that to your results.

Thanks Corey, and thanks again for the cams to do the experiment!
I think you're right, probably had a little more hp before it dipped, though I don't know if I'd want to push it more. It was already 1K over the 10K redline when they stopped the dyno run.
Interesting that max torque didn't change much, from 28.1 to 28.7 (2%) vs the 7% increase in horsepower.
I would like to shift the powerband down a bit, otherwise I'm going to spend too much time going too fast chasing the 9-10K rpm sweet spot. I'm pretty sure that contributed to the death of a poor squirrel during my last ride.

Missing from the graphs are the air/fuel "mean" or ideal line. Maybe I can't see it? Dyno Jet has an ideal air fuel line at 13.2. I know the Factory Pro is different in their readings, and how power is read. What is their ideal air/fuel?

Could you list your current carb settings for the Factory Pro Kit in your CV30 Carbs:
Main Jet
Pilot Jet
Needle and clip setting with/without shims(starting from the top)
Float height
Mixture screw settings

Thank you!

We all have not doubt seen Factory Pro's CV Carb Tuning Guide, but for reference, here it is:
www.factorypro.com/tech/tech_tuning_proc...igh_rpm_engines.html

EDITED:

Thanks Corey, and thanks again for the cams to do the experiment!

You are welcome! As I said before, anytime you want to change back to the ZR Cams, I will be more than glad to assist you in my garage. If you will eventually go 615, with other cams spare cam gears you have, it would be good to think about having them slotted.

I think you're right, probably had a little more hp before it dipped, though I don't know if I'd want to push it more. It was already 1K over the 10K redline when they stopped the dyno run.

Yes, they should have kept going with the running past the red line on the tach. You should know at least where it peaks. It's like the letter "o" that isn't closed completely, so it is a "u". LOL!!!

double post

When I use a wideband AFR and let the RPMs go to redline, my target AFR is about 13.0 . My butt notices maybe a tad more power if I go slightly leaner, like 13.2, maybe even 13.5, but then you're heading for danger. The goal is to have the AFR sweep through the 12's as the RPMs increase.

CoreyClough wrote: Could you list your current carb settings for the Factory Pro Kit in your CV30 Carbs:
Main Jet
Pilot Jet
Needle and clip setting with/without shims(starting from the top)
Float height
Mixture screw settings

These are my current settings:

Main Jet = 112 for carbs #1,4, 115 for carbs #2,3
Pilot Jet = 35
Needle = 0968h-66u, /2 clip position with 2 washers above clip
Float height = 17mm
Mixture Screw = 3 turns out

CoreyClough wrote: Missing from the graphs are the air/fuel "mean" or ideal line. Maybe I can't see it? Dyno Jet has an ideal air fuel line at 13.2. I know the Factory Pro is different in their readings, and how power is read. What is their ideal air/fuel?

The only gas-related line in the graph is the CO%/acc line, which is a measure of partially burned fuel. I'm not sure there's an "ideal", I think we'd want it as low as possible but each engine will have a different baseline efficiency. All the advice they've given me so far seems to be aimed at making the line as low and flat as possible. I asked Marc for more info on how to interpret the line - will report back.

We do have additional gas measurements in the charts, though it looks like NOx is missing in the most recent dyno (unless it was really 0 which seems hard to believe). Each gas is an indication of a different aspect of the burning process. Here's a little excerpt I found online about using a 4 gas analyzer -

If not AFR, what? We use a 4 gas exhaust analyzer to tune the engine. When fuel is burned it is a chemical reaction. The chemical reaction gives off by-products, these are the emission. CO, CO2, HC and O2 are all emission in the exhaust gasses. AFR only looks at the O2, the least important in the equation. Carbon Monoxide, CO, is partially burned fuel. Carbon Dioxide, CO2 is fully burned fuel. Hydrocarbons, HC is raw unburned fuel. Oxygen, O2 is left over that isn't used in the combustion process. In a perfect world all the O2 is combined with all the HC during the combustion process, this doesn't happen. We use a high speed 4 gas analyzer to look at the exhaust gasses and then adjust for a proper burn. The gasses tell us how the timing is, if there is too much or too little fuel for the amount of oxygen available etc.

Yes, there are some assumptions you have to make when tuning with only an o2 sensor.

For instance, if your mixture is so rich that it doesn't burn, then there will be a lot of o2 in the exhaust. This makes the AFR appear to be very lean... the opposite of what is really happening. Also, if you have a misfire from an ignition system problem, you will get hesitations which will indicate as very-lean. So you might think you have a fuel problem, when in fact it's something else.

But if you work with a wideband system you will eventually be able to determine these false inditations for what they are. After tuning a few bikes with the wideband, you will wonder how you ever lived without one.

So even though AFR is a single, maybe simplistic, indicator, it is still extremely useful, and with experience it's all you really need for carbs. The only real downside is if you only use one sensor. Then you have to make sure all four cylinders and carbs are working the same. 4 sensors would be ideal, but the wiring could get a little cumbersome.

Zaddict wrote:
These are my current settings:

Main Jet = 112 for carbs #1,4, 115 for carbs #2,3
Pilot Jet = 35
Needle = 0968h-66u, /2 clip position with 2 washers above clip
Float height = 17mm
Mixture Screw = 3 turns out

Those are the same exact settings that I am using, but I am still using the stock main jets as instructed by the Factory Pro setup sheet.
#108 (1&4)
#110 (2&3)

But since you are using a freer flowing exhaust, I would have figured that the #112-115 jets would be needed. But apparently not....very weird.