TOPIC:

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?

.please correct me if this is wrong!

I think the ZR550 cams are 248, not 270. They are mild for punchy bottom end and midrange, I think the same grind as the pre gpz z550 series.

Remember the cams work half the speed of the crank, so a tooth out doubles up the error when measured as degrees of crank rotation.

Tyrell Corp wrote: .please correct me if this is wrong!

I think the ZR550 cams are 248, not 270. They are mild for punchy bottom end and midrange, I think the same grind as the pre gpz z550 series.

Remember the cams work half the speed of the crank, so a tooth out doubles up the error when measured as degrees of crank rotation.

I had to refer back to the factory service manual and it states that the zr550 duration is 270°.

Brendan, in the U.S. we have the Zr550B which uses the "two-groove" grind (270 duration), which is the same as the 550D and 550H gpz. In Europe, there is a Zr550A, which has the nicely confusing marketing name of Z550F, that looks very much like a 550H Gpz, but without the front fairing. That bike uses the no-groove standard grind cams (248 duration).

Corey, I believe the published cam timing specs are checked with zero lash and are based on the assumption that the timing marks line up perfectly at TDC. With those parameters, I get very close to the published specs reliably. We know for a fact that the published specs are not exactly correct for the Zx as the sprockets show it to be impossible. But the published specs are only off by a degree or two such that the total difference is about 3 crank deg.

Not to be too critical on this, but my readings will be testing the cam profile of the ZX Cams on a ZX Engine. I don't want to overtake this thread, but in all my GPz Years, I have never needed or wanted, to check cam timing. I will only be taking readings from #4 intake and#4 Exhaust Cam Lobes because they are easy to get to. The valves will be checked and gapped within the recommended settings before taking readings. This information should be useful.

Thoughts?

CoreyClough wrote: Not to be too critical on this, but my readings will be testing the cam profile of the ZX Cams on a ZX Engine. I don't want to overtake this thread, but in all my GPz Years, I have never needed or wanted, to check cam timing. I will only be taking readings from #4 intake and#4 Exhaust Cam Lobes because they are easy to get to. The valves will be checked and gapped within the recommended settings before taking readings. This information should be useful.

Thoughts?

I think you are doing it the right way for real-world setup on a race bike.

I assume you find true TDC of the crank with a feeler of some sort on the piston in order to justify a degree wheel to the crank, then use a dial indicator to identify the #4 lobe centers (where the valve is open the most) to set the position of the centers relative to TDC/BDC? That is how it should be done as long as you have slotted sprockets to get the timing precisely where you want it.

Using the sprocket timing marks and cast-in crank pointer to time the engine is a short-cut method to get you close.
And with a lot of figuring, you can get two or three discreet timing options depending on which sprockets you have, but that amplifies the complexity by several times,

I'm doing a different thing. I am trying to see how close the actual cams and sprockets come to the published specs. After measuring several cams of each type (only two Zx, though) I can see the published specs are within about 2 or 3 degrees of what they claim. So if you use the shortcut method of cam timing (the factory service manual method), and everything lines up perfectly (which it never really does), the closest you will come is a couple/few degrees off. Good enough for government work.

man, I'm loving this thread. So much helpful info.

I owe you guys some dyno results but I can tell you already the bike is running super strong. Forget everything I said about the last test ride - I'm 99% sure the problem was that my clutch was slipping. I was even thinking that day that the bike was louder than usual but didn't mention it because I didn't see how that could make sense, but now that I'm thinking about it, it was probably louder because it was revving higher than usual. I've been riding the bike around the city and took it for a short run on the highway yesterday. It's got plenty of power across the full rpm range. Maybe slightly down on the low end (hard to tell), but almost certainly up on the high end.

loudhvx wrote:

CoreyClough wrote: Not to be too critical on this, but my readings will be testing the cam profile of the ZX Cams on a ZX Engine. I don't want to overtake this thread, but in all my GPz Years, I have never needed or wanted, to check cam timing. I will only be taking readings from #4 intake and#4 Exhaust Cam Lobes because they are easy to get to. The valves will be checked and gapped within the recommended settings before taking readings. This information should be useful.

Thoughts?

I think you are doing it the right way for real-world setup on a race bike.

I assume you find true TDC of the crank with a feeler of some sort on the piston in order to justify a degree wheel to the crank, then use a dial indicator to identify the #4 lobe centers (where the valve is open the most) to set the position of the centers relative to TDC/BDC? That is how it should be done as long as you have slotted sprockets to get the timing precisely where you want it.

Using the sprocket timing marks and cast-in crank pointer to time the engine is a short-cut method to get you close.
And with a lot of figuring, you can get two or three discreet timing options depending on which sprockets you have, but that amplifies the complexity by several times,

I'm doing a different thing. I am trying to see how close the actual cams and sprockets come to the published specs. After measuring several cams of each type (only two Zx, though) I can see the published specs are within about 2 or 3 degrees of what they claim. So if you use the shortcut method of cam timing (the factory service manual method), and everything lines up perfectly (which it never really does), the closest you will come is a couple/few degrees off. Good enough for government work.

I don't plan on adjusting cam timing, just taking the readings as the cams are installed now. I do have a piston stop tool, degree wheel, and dial indicator. I'll take the readings, and plug in the numbers. I'll even try it with as close to zero valve clearance as possible. I do have a set of slotted cam gears I could install at a later date, if I wanted to adjust them to a specific timing. For now, if they are close, I'm leaving them where they are.

Glad you rechecked the "seat of the pants" on your set up Mark. We can always set it back to where it was with the other cams if you ever wanted to.

I will have to get these readings next weekend, and as Marcia Brady said, "Something suddenly came up".