TOPIC:

We did check stock ZR Cam Timing before we removed the cams. I marked the cam chain pins and the cam gear, before zip tying the gear around the cam chain. The intake cam was installed in the same holes, and the lobes were in the same position. Checked and adjusted clearances and then rechecked with my valve cover tool in place and the manual tensioner tightened. The same process was used for the exhaust cam replacement.

The only thing I wish we would have had time to do, was measure the cam timing with dial indicator, and degree wheel to get actual cam timing before and after the cam swap. I wouldn't think the change in duration from the ZR to the ZX Cams is all that much different to have the end result feeling what Mark is getting with the poor gas mileage. No suggestions for poor fuel mileage, but I'd check for the possibility of vacuum leaks, and or cam timing off?

I looked up cam duration change only, with lift remaining the same, and came up with the following:
"Increasing duration keeps the valve open longer, and can increase high-rpm power. Doing so increases the RPM range that the engine produces power. Increasing duration without a change in lobe separation angle will result in increased valve overlap."

Mark is still using the stock air box, but might not be for much longer, as I saw him fight to reinstall the carb rack. Throttle cables remained attached to the carbs, but moved the carb rack off to the left side to gain access to the manual cam chain tensioner.

I agree cam timing should be rechecked before going any further in diagnosis.

We only moved the clutch cable out of the way, but did not disconnect it or loosen it from either end. If the clutch is indeed slipping, that would need to be addressed too.

Mark, I have a wide range Factory Pro Main Jets for when the time comes. Get a few sets of bowl gaskets when you head to the dyno, but make sure to bring back the extras before you leave. LOL!!!

Here is an interesting V-8 read when just changing the duration of the cam:
www.powerperformancenews.com/tech-articles/the-duration-game/

The intake cam was installed in the same holes, and the lobes were in the same position.

???Have you ftted ZX cams to ZR cam sprockets using the same timing holes?

There are three pairs of holes giving diifferent cam timing for the same alignment marks and top run pin count. ...you need the xz holes.

These longer duraton 280 degree cams open and close later, the ZR550 is much less duration - 246 degrees?,

I am running running 102 intake timing using the ZX gears, but different bolt holes. The ZX Exhaust Cam is in the stock ZX Holes. I have moved my intake gear to the hex holes (originally from the square holes), and in doing so the cam moves counter clockwise enough to retard the intake cam timing very close to 102 . See attachments below, of where my intake cam is when this is achieved. Notice the timing marks on the intake cam gear are no longer on the Z4 IN Mark, but the Exhaust Cam is in the stock location. This is my engine currently running. According to Lou's information, "Each sprocket has 42 teeth. Each tooth is 360/42 degrees on the sprocket. That is approximately 8.57 degrees."


In this last picture, you can see where the intake cam is in the Hex Holes, and the square hole is where the intake gear is in line with the head surface, like that of ZR Timing.

On Mark's, we only installed the ZX Cams in the stock ZR Holes on the ZR Sprockets retaining the stock ZR Cam Timing. The ZX holes on the ZX Cams are only needed to run ZX intake timing of 94. Both ZR and ZX use the same exhaust gear to get 104, but we left the ZR Exhaust Cam Gear in place, only changing the Cams only. Cam lobe position on both ZX and ZR Cams are the same, only the ZX has more duration. Mark has the set of ZX Gears if he wants to switch them out, but I'd like to see if there is anything else that could possibly be the result of his poor performance before doing this.

For the record, I have this Sunday off, and can record the settings on my engine with the ZX Cams set up this way. This will give a true reading. The steps I follow are on the Web Camshaft Site here:
www.webcamshafts.com/

Am I missing something that you are stating Brendan?

I figured you would swap the intake and exhaust sprockets in order to use the Kz/Zr timing. That way you can see both timing marks EX and Z5. With the sprockets as is, you don't see a Z5 intake mark, correct? Not that you need it. It's apparent where it would be and you are just counting links, but when you put on the see-through valve cover, it would be nice to see the little line line up with the deck.

I will get those for you. this weekends.

If I may, I would like to add some visual aids to help us less camshaft savvy readers follow along.

I was trying to figure out how much valve overlap was lost/gained during this swap so I could make sense of where and why the power band would have moved. It became confusing because of the use of the longer duration zx550 cams with different degree-of-lobe-center Zephyr sprockets.

The lower (narrow) the LSA ( Lobe Separation Angle) leads to a higher amount of valve overlap = Power is moved to the mid to high range.
The higher (wider) the LSA leads to a smaller amount of valve overlap. = Power is moved to the low to mid range.
The more valve overlap there is, the more the dynamic compression in the combustion chamber goes down and power is lost in the lower RPM's.



Stock zr550


Stock zx550


Zaddict's current setup with zx550 cams and zr550 sprockets


In summary....please correct me if this is wrong!

Zaddict only gained 10° more valve overlap from using the Zephyr sprockets, so the power only shifted up slightly and less dynamic compression is lost. (This is important because he is still using the lower compression pistons that came stock with Zephyr 550. )
That is great, because the 94° zx550 sprockets with the longer duration cams would have given him 20° more valve overlap, more compression loss and loss of low end power. So any power gained would have moved even farther up the power band.
So by mixing and matching sprockets and cams, the LSA actually stayed the same, but overlap was reduced. Clever.....but confusing right?

I wish I had knew about this years ago, so I could have set my intakes at 102° or 104° as well!

Kawasaki actually kept the advertised cam specs pretty simple on the 550 motors.

All of the cams are symmetrical.

Intake and exhaust cams have the same profile for every 550 motor. (I assume same is true for the 400 and 500.)

They all index the same, meaning if you mount any camshaft in the same sprocket holes, the lobe center will be at the same position.

All of the cams will index to 104/104 if you use Z/5 and EX timing marks.

All sprockets start out as the same stamping. That includes intake and exhaust.

The only difference is the 6-hole sprocket. It allows for one additional index position than the normal 4-hole sprocket. This was originally used on the intake of the smaller Kz400J motor. That motor was the same as a Kz500/550 motor but with even smaller displacement. The Zx550 uses the Kz400J intake timing, hence the usage of the "Z4" timing mark for the intake on the Zx550. The extra pair of holes indexes the intake camshaft forward by 10 crank deg (if the published specs were accurate).

So really, if you always use "EX" for exhaust, and only swap intake between Z/5 and Z/4, and if the published specs were accurate, you can only change duration by 10 crank deg. That is because you are simply moving one camshaft by 10 deg. It doesn't matter how much overlap a pair of cams have, the sprocket change will always produce a 10 deg difference in overlap.

Calculating overlap using the Kawasaki published specs is very easy. You just add the EX close value to the IN open value.
It's not necessarily that simple if you go to larger lift values for timing specs.

The actual amount of overlap depends on what lift you use to compare them. When you are using the factory published specs, you are using approximately .012" lift with zero checking clearance as your spec for the duration. The factory is likely using a nominal 0.3 mm, but all of my tools are in inches so .012" is what I use.

But if you use higher lifts for comparison, like some other companies do, your overlap can change dramatically. You might even get negative overlap, which is a gap between intake and exhaust. In that case, advancing the intake cam 10 deg might only reduce the gap, so there would still be no overlap.

For example, if we use .050" as the lift, I measured the duration as 227 on a two-groove (Zr) camshaft. The centers are still 104/104. Then we have:
I.O. 9.5 BTDC
I.C. 37.5 ABDC
E.O. 37.5 BBDC
E.C. 9.5 ATDC
Then the overlap is merely 19 crank deg.

One issue to keep in mind is that the published specs are inaccurate. The difference between "Z/4" and "Z/5" is closer to 7 crank deg., not 10. The actual lobe centers are not exactly 104/104.

None of the above includes the added variables of crank position, chains, chain-guides, chain stretch, lash, etc. etc. The above only includes sprocket-to-cam and cam-to-valve relationships as measured on an actual head. It assumes the timing marks perfectly line up exactly at TDC.

When I check my cam timing this weekend, I will us the .040" and .050" as the two starting points. I will not be doing this at "zero" valve clearance., but I have in the past, once the clearance was set, I'd install the closest feeler gauge to get the clearance to "zero" and take readings, but is bends the crap out of the feeler gauge. I normally start at .040" as that is what I've used when degreeing my Megacycle Cams. When doing those cams, getting the lobe centers to their recommended 105/108 is all I shoot for in adjusting them,. Oher than makin sure the valve clearances are within spec, and of course piston to valve clearance is good, but once these two are done, it's adjusting for lobe centers.

I offered to check Mark's Cams this weekend as well, but he will not be able to come over. In an e-mail, he seriously thinks his clutch is slipping, but we won't know his "seat of the pants" results until he fixes that, and rechecks for everything else.

Thanks for all the great information added to this thread.

That's a great post!

My only issue with diagrams like that, below, is that it tends to confuse people.

Daftrusty wrote:

People may interpret the image as if it is a drawing of looking down the end of a camshaft. Obviously, on a Kz four, all of the lobes will be physically spaced at perfect 90 deg angles from each other.

The other problem with graphics is that we are working in crankshaft degrees, so our cams actually have 720 deg per rotation. It's sometimes easy to lose that in our 360 deg minds, at least for it is.

That diagram shows the lobe separation in crank degrees, but the lobe shape, as it's drawn, implies cam degrees, so there is sort of a conflict of interpretation.

I don't have a better suggestion, as I haven't seen any cam timing diagrams that were instantly self-explanatory.

They tend to look like this, and it's what mine look like, but it's not exactly "speaking" to me.


Actually, mine tend to be more rustic :

You are correct! I should have labeled that diagram as it only illustrates what LSA’s are and the little triangle between the lobes that illustrates the valve overlap.
But we have completely separate intake and exhaust cams, so it is confusing instead of clarifying like I hoped.

I also started drawing out the cam timing graphs for the different setups and it quickly became less helpful when comparing the three. So I switched to an online calculator as it made for a better numerical visual aid.

Not very helpful

Nice work there!

Are this the theoretical readings, at zero clearance?