gpz 550 cams in a kz550 or zr550?

They are totally different bikes. Compared to the the 750 the 550 feels so light. Almost like bicycle light. It is so nimble and easy to fling around. Not that the 750 feels like lumbering beast that is hard handle, (quite the opposite) it just obvious how much heavier it compared to the 550 when trying to fling it around or do tight u-turns in the driveway.
The 550 also just wants to rev. When giving the 550 the beans, it just takes off and effortlessly screams all the way into the redline with no sign of stopping. ( I love this about the 550's ) The 750 just has grunt that shoves you forward and rises in rpm's until it eventually runs out of steam. ( I also love the grunt of torque)

Yes, very different bikes. I prefer the better frame bracing on the 750, and something about the steering geometry feels just so right. The 550 has that close ratio six speed box which I like plus that engine that just wants to redline every gear. I suspect in the right hands there would be little difference in performance between them. Both the twin shock models share that one year rarity plus the iconic GPz silhouette.

On the cam timing, that 92 degree lobe centre INlet cam setting is odd - I spoke to a cam expert at Kent Cams UK about this but didn't get any defintive reason. He recommended a 108 /112 setting though - pretty much what I had been running.

loudhvx wrote: The Zx cams I measured have the same lift as the D and H cams, but the duration is longer. Is Mark getting higher compression pistons? The D and H are 10:1 while the Zr is 9.5:1.

Mark is running the stock ZR550 Pistons, and will be adding the ZX Cams. He will be the Guinea Pig on this. His current cam timing is correct for the better intake, so we will swap just the cam there, and re-shim, then do the same with the exhaust cam. If indeed the lift is the same, the different duration I would think should not interfere with the PTV Clearance.

We will obviously post out results here..

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Is it possible to fish a length of soldering wire in through the spark plug hole and use that as a “plastigauge” of sorts to measure the piston to valve clearance? Hand cycle the engine then pull the length of solder out and measure.
Just for sake of scientific data?

So from the Office Space picture above of The Bobs, "hypothetically speaking here", if both ZR and ZX Cams have the same lift, measuring P2V would not be needed, IF we are using the same ZR Cam Timing. Lou has stated, it is just the duration that is different in the two cams. If the lift was greater than the stock ZR Cam, then yes, P2V would need to be checked. I am not saying I am right here, but just thinking out loud, Not too radical of a duration change from the ZR to the ZX Cams.

Edited after thinking:
Rethinking this after reading this from a search on P2V, but it is describing a single overhead cam:

"Advancing or retarding the camshaft will also affect P2V clearance. Advancing the cam helps build low-end torque but it also decreases the intake P2V clearance while increasing exhaust clearance. It’s the just the opposite for retarding cam timing when higher RPM power is desired–increased intake P2V clearance with decreased exhaust clearance."

So, when the piston is at TDC the P2V is checked, so duration might come into play here.

Higher piston crown on the ZX Pistons would have deeper valve pocketing, than the ZR lower piston crown, right?

Thoughts???

The taller zx pistons had valve pockets with a deeper bottom than the Zephyr pistons. I set the pistons next to each other and measured to the bottom of the intake pocket from a datum line and it was over 1mm deeper.
I am out of town right now, but I have both zx and zr pistons and cams at home. So I can try to remeasure them and provide pictures for documentation when I get back home if that would help?

Tyrell Corp wrote: On the cam timing, that 92 degree lobe centre INlet cam setting is odd - I spoke to a cam expert at Kent Cams UK about this but didn't get any definitive reason. He recommended a 108 /112 setting though - pretty much what I had been running.

Is the 108/112 setting possible with stock cam sprockets? How does that affect the power curves? So many options here.

I'll guess we'll know about piston-to-valve clearance in a few hours - headed over to Corey's then to do the surgery. Assuming we have a way to measure that...I might bring some solder in case to try Russell's idea.

Zaddict wrote:

Tyrell Corp wrote: On the cam timing, that 92 degree lobe centre INlet cam setting is odd - I spoke to a cam expert at Kent Cams UK about this but didn't get any definitive reason. He recommended a 108 /112 setting though - pretty much what I had been running.

Is the 108/112 setting possible with stock cam sprockets? How does that affect the power curves? So many options here.

I'll guess we'll know about piston-to-valve clearance in a few hours - headed over to Corey's then to do the surgery. Assuming we have a way to measure that...I might bring some solder in case to try Russell's idea.

The piston to valve clearance question is really only regarding Gpz pistons. Your Zr pistons should not have an issue since they are not as tall. The clearance to the pockets will be reduced, but it's difficult to predict actual numbers.

Even if maximum lobe lift is the same, longer duration means the valve will be open more at various points in the lift cycle, even though it won't be open more at the peak lift point. Because of this, you still need to check clearance.

The interference point is not likely to be at the maximum lift point as the piston will be down considerably at that point. The interference will be at some lower valve position during the closing of the exhaust valve or the opening of the intake valve. That's when the piston will be closest to the valves. That's why the duration can effect the possibility of interference.

I have a Gpz D motor that's apparently been shaved, and I can hear what sounds like valves nicking pistons if the motor is really hot after shutting down and restarting. For a few seconds before the oil pressure comes up fully, I have to really be easy on the throttle or the noise becomes apparent. As long as I wait or give it really slow throttle it's quiet. After a minute I can ride it normally. So the clearances must be pretty close at some point in the piston's motion. A longer duration could conceivably take up the clearance.

Regarding timing: You can alter the timing in some increments using the factory sprockets, especially if you have two Zx intake sprockets.

There was discussion about actual cam timing differences between the Zx and Kz. Kawasaki advertises a 10 deg difference on the intake cam, but every way I measure it, it comes up less. The actual number is closer to 7 degrees. This was confirmed by others on the Gpz forum by staking sprockets and looking at the teeth offset. I measured it using trig.

The page describing the measuring method also describes the sprocket position relative to cam timing in great detail, and shows how you can get several different timing options by using different mounting holes in the sprockets. But only a couple would actually be useful.

The increments are roughly 4.6, 6.0 and 6.8 crank degrees depending on what holes you start at, and which holes you move to.

So assuming the intake using square-marked holes gives a 95 ATDC (as the Zx comes from the factory),
moving (retarding) from square-marked to hex-marked holes gives 102 ATDC (as the Kz comes from the factory).
Moving (retarding) from hex-marked to circle-marked gives 108 ATDC.
Moving (retarding) from circle-marked to square-marked (again) gives 112 ATDC.
So as you can see, going through the whole cycle of sprocket markings gets you 17 degrees of movement broken up into 3 smaller (unequal) movements. That 17 degrees of movement equals one sprocket tooth.

Note: remember that all angles are specified in crank degrees. One tooth on the sprocket is only 8.57 degrees of the sprocket, but that translates to 17.14 crankshaft degrees.

s3.amazonaws.com/gpzweb/CamsKZZXZR550500...e/SprocketGauge.html

Both ZR550 and ZX550 Cams have a the same overall lobe height of about 1.430” as measured with dial calipers from bottom base circle to high point. This is not the lift.
Base circle is about 1.112”, so that equates to a lift of about 0.318”.

Both cams have this same result.

Measuring my Megacycle Cams (478-60 Grind), results in the following:
1.095” Base Circle
1.505” Base Circle and Lobe Height
0.410” Lift

www.google.com/search?q=How+to+measure+c...imgrc=Hv44BLkRwQBf6M :

Hi Corey, the base circle consists of less than 180 degrees of the actual cam rotation, so you cannot measure the actual base circle directly as you have it shown. The areas you point to as being the base circle are actually at a larger diameter than the base circle. In other words, the cam is wider on the sides than the base circle would be. To measure the base circle you have to put it into a head or some other contraption and spin it to find the difference from the point of the lobe to the heel of the lobe. That is the true lobe lift, and from that you calculate the base circle by subtracting lobe lift from the overall cam measurement.

Your measurements for overall cam height is about what I have. (They all vary a bit.)

See how I measured the cams on the valve train page in my signature. It's down toward the bottom.

Thank you for this valuable information. It is news to me.

Nice talking to you on the phone today.

Same here! Hope the ZR turned out good.

To measure the base circle you have to put it into a head or some other contraption and spin it to find the difference from the point of the lobe to the heel of the lobe. That is the true lobe lift,

Yes, but in my experience with used parts of often unknown mileage and service records, this ' zero lift' factory spec duration is really difficult to get...there is a some run out plus wear ... like this factory 'at the crank measurement' advertised bhp Kw Din number vs real world rwhp bhp dyno sheets.

I made up a cam tester with a dial gauge and some scrapped cylinder head caps pairs doubled up , then tested half a dozen 550 cams from various models - the duration results were not as expected.

Plus the head fuck of wear /factory tolerances issues y .040" or .050" lift duration that performance cams manuafucurers compare to.

Good thread keep it coming.