Cylinder head resurface, cam timing?

I studied steell's post, but I'm tired and couldn't make sense out it. will try tomorrow.. Meanwhile as I was checking your figures of valve opening/closing, it appears that the cams are working about 15 to 20 degrees too early. I discounted your last readings with the .040 reference as then the valves were not staying open as long ie:had a shorter duration than stock (you are running stock cams-yes?). Is the front cam chain runner and guide in the cylinder there and and the chain is properly in place? Try moving the cams (both of them) BACK one notch/tooth. Turn engine by hand to make sure that nothing is hitting. If ok then do compression test. If compression raises then try starting it. I know this sounds CRAZY!! But after drawing it out on paper (using your degree wheel specs) I see where both cams are working and where they should be working and they are EARLY. With the head being milled it might make the cams work a tad bit late not early. Be sure to keep the 28 pin count. I don't think having the cams off by 1 tooth will hurt anything, it didn't on mine when I goofed once. Just can't remember for sure if it ran hot as well as slugish... TFH...

79MKII wrote:

Wow...I'll be watching this one closely. I have a head at the shop right now and they also plan on milling it just enough to make sure it's flat. The guy told me it's usually only around .020" or so and it shouldn't make much of a difference (about 1/4 point of compression). One thing for sure though, milling the head will INCREASE compression, not lower it. I'm very curious to see what this could be. Hopefully someone can help out.

Hope .020" is a typo

Jay

APE Jay wrote:

79MKII wrote:

Wow...I'll be watching this one closely. I have a head at the shop right now and they also plan on milling it just enough to make sure it's flat. The guy told me it's usually only around .020" or so and it shouldn't make much of a difference (about 1/4 point of compression). One thing for sure though, milling the head will INCREASE compression, not lower it. I'm very curious to see what this could be. Hopefully someone can help out.

Hope .020" is a typo

Jay

I don't know much about the 1000's, but I know that .020" is not the max on a 750, is that radical for a 1000/900??

Hey guys I have a thought. I noticed that you have new bolts on the cam sproket(s). Well is it posible that the cams got put onto the wrong sprokets. meaning his exhaust cam is on the intake side and vice versa???
:blink: I also noticed that one cam looks to be new. Is it the right cam.
Just an outside thought:dry:

Post edited by: Snakebyte, at: 2006/01/09 03:41

Whew after sleeping on it, You have to have something else wrong. Either your not reading the degree wheel correctly (remember the crank and cams rotate in clockwise direction as looking from right side of engine), You are saying ie: intake is opening at 45 BTDC when it should be 30BTDC, exhaust is opening at 85 BBDC when it should be 70BBDC. But the timing marks at crank and cams sure look to be correct. If not for the degree specs I would not say move cams back 1 tooth. Recheck to make sure that "0" TDC on degree wheel and "T" on ign advance and #1 piston all say TDC at the same time. To have low compression the problem has to be mechanical, not electrical. Getting hot and poor running can be any or mix of mechanical, electrical, fuel. Moving cams back 1 tooth is not a fix but a proof that they are in fact working early. Will still have to find and correct the WHY. Before running check them with the degree wheel and see where the cams are at... Got to go... Good luck.. hopefull some else may have an idea...TFH

I might try moving the cams back one link tonight.

Thanks Snakebyte for the thoughts on the cams. No I don't have any new ones. I have three sets of cams and I picked the best looking ones (least scratches and wear)to put on the bike. Visually I couldn't tell any difference in actual cams, and the Parts Diagrams on Kawasaki show the same part numbers for 76-80 models. I think the intake that is in it had a 32 tooth sprocket on it though so I switched the sprocket out for the 30 tooth one. The exhaust cams all have the gear for the tach drive, the intake ones don't have the gear so I don't think I got them mixed up. I know people have rebuilt hundreds of engines and not had these problems. I also wondered if in mixing these parts up I have inadvertantly put something where it shouldn't be.

I printed out the thread from Steell and I will study it this morning.

Thank you ALL for the help and concern. I actually think my wife wants me to keep working on it so I'll stay in the garage and not bother her.

steell wrote:

APE Jay wrote:

79MKII wrote:

Wow...I'll be watching this one closely. I have a head at the shop right now and they also plan on milling it just enough to make sure it's flat. The guy told me it's usually only around .020" or so and it shouldn't make much of a difference (about 1/4 point of compression). One thing for sure though, milling the head will INCREASE compression, not lower it. I'm very curious to see what this could be. Hopefully someone can help out.

Hope .020" is a typo

Jay

I don't know much about the 1000's, but I know that .020" is not the max on a 750, is that radical for a 1000/900??

It is for this thread. It is about surfacing the head and not changing cam timing much. .020" ( twenty thousanths, or .5 mm) will definately retard the cams. I think he ment .002"

Jay

It will be a few days before I get the adjustable cam sprockets. In the meantime I have been dinking with the degreeing wheel some more. I swapped shims in #1 intake valve and took out most of the valve lash. Still using .040" lift I got virtually the same numbers as before.

However I found if I used 0.25 MM (.010") lift the opening is at 31 BTDC and Closing is at 71 ABDC which is almost correct. Could the stock cam specs be measured at 0.25 MM lift?

Thanks!!!

Well, if you look at the link I posted you will see that the 750 cams are rated at .25mm
I don't know if the 900/1000 is rated the same way, but I assume they would be.

I bet APE Jay could answer

Post edited by: steell, at: 2006/01/09 23:34

Willo46 wrote:

It will be a few days before I get the adjustable cam sprockets. In the meantime I have been dinking with the degreeing wheel some more. I swapped shims in #1 intake valve and took out most of the valve lash. Still using .040" lift I got virtually the same numbers as before.

However I found if I used 0.25 MM (.010") lift the opening is at 31 BTDC and Closing is at 71 ABDC which is almost correct. Could the stock cam specs be measured at 0.25 MM lift?

Thanks!!!

Are you calling "lift" the space between the cam and the valve shim in bucket?

steell wrote:

Well, if you look at the link I posted you will see that the 750 cams are rated at .25mm
I don't know if the 900/1000 is rated the same way, but I assume they would be.

I bet APE Jay could answer <br><br>Post edited by: steell, at: 2006/01/09 23:34

Don't try to use .25mm. That is only .010", and at that point you are still on the heel of the lobe and it is way too inaccurate. If you use .040" ( most racers use .050"), you are up the ramp and it is much more accurate.

Using lobe center method, you can go up to .050" and get a good accurate reading.

Jay

The link I posted confuses me :silly:
It states .25mm lift 8.0mm lift, and that must be the valve clearance and the total valve lift, and the total lift don't matter when you are checking valve timing.
The standard for automotive cam specs is .050" (even though not all manufacturers adhere to it), but I don't know if a different standard is applied to motorcycle cams. The fact that your measurements at .010" are reasonably close to the stock specs make me wonder if that's not what Kawasaki specs their cams at.

Please clarify one point, was your head milled .002" or .020"? If it was .020" then you will need to elongate the cam sprocket mounting holes (or buy slotted sprockets) in order to get the cams right.
.
.
From oldkawmans site:

More confusion ensues when the duration is defined according to lift.
Manufactures such as Kawasaki say that they have 280 degrees of duration OEM.
They give no reference. That means @0.001 inch lift. Aftermarket usually give
@0.050 lift as the reference. Some now give @0.030 inch lift. The OEM cams
could be described as having 220 degrees duration @0.050 lift. You simply ignore
the time the valve is open until it is open a distance of 0.050 inches. Then
measure duration until the valve is 0.050 inches from closed.

www.oldkawman.com/okndrebuild.html
.

And a "How to degree cams" by WebCams:

www.webcamshafts.com/degreeing.html

Post edited by: steell, at: 2006/01/10 01:04