CAM DEGREEING Removed...

Yes indeed confusing the way they had written it up and that is why I provided a d different calculation/formula, works out 100% the same and there's no need to remember all the mumble jumble crap...

NOTE: Works in both intake and exhaust recrodings!
Formula is Larger number - smaller number /2 + 90.

Example using the supplied recordings....

Exhaust opens (at 1mm lift) 60 BBDC
Exhaust closes (at 1mm lift) 40 ATDC

60-40 = 20/2 = 10 + 90 = 100 lobe center...

Can't get any more easier than that.

OMR

you did hit the nail:woohoo:

thats exactly how I do it....

I would love to find some hard figures about lobe centers and dynoruns with torque values.. but these are exctincted I geuss.
And I geuss there are not so many people who can really set a cam properly......

anyway good topic!

I guess parts designed years ago, might of been built and tested on smaller bore motors. Now days most people go for the bigger sizes.Yet, I have not seen any new tech parts for Z's lately. Who knows, but I would like to see more of the old racing serects come to light.

It doesn't matter what math you choice, Isn't the point to time your cam the best you can? The two most common methods of cam degreeing are "Split Overlap & Split Center Line".

I guess my point is, Not the methhd. (you can buy a video on that) My question is the behavior of your motor due-to your cam timing.If you pick the cam timing, what kind of animal are you getting. I'm not just talking about the old, more botom end or more top end.

Some cam companies sell cams with matching lobe centers
(say,108*/108*) and some are different (say, 106*/108*)
And then here we come to change that. Why? We are hoping to find more power,to change how our animal will act. You could buy the best cam in the world and then time it your way, maybe it's good or maybe it's crap.

Z1 cam timing, has changed the world. Honda car tuners are eating it up! It was the 1st. real motor you could make these choices happen in.

I am listing three ways of timing Z1 cams. Could someone Please label them for Characteristic. Not the bottom-end / top-end thing. I would like to know witch ones are broad & witch are narrow peakie power bands.


Group #A

Intake advanced - bottom end/mid range.
Exhaust advanced

Intake retarded - Mid range/top end.
Exhaust retarded

---

Group #B

Intake advanced - bottom end/ mid range.
Exhaust stock

Intake retarded - Mid range/ top end.
Exhaust stock

---

Group #C
intake retarded - bottom end/mid range.
exhaust advanced

intake advanced - mid range/top end.
exhaust retarded

---

I will take the 1st. guess: Here is my GUESS.

Group #A = Wide broad power band.
(street,good all around)

Group #B = Wide power band.
(street, roadrace)

Group #C = Very narrow peakie power band.
(not for street with low L/C)



Everyone please give all the in-put that you can...Thank you.

Dude.. you're putting way too much into this...

As provided to me as I was doing the same as you...

NOTE: This was for my 1015cc, .365 cams @ 105 LC...

You won't notice any difference between 105 -108 that will be anything to write home about. To put bottom end in the motor, you would advance BOTH cams, NOT pull low lobe centers on both cams.

Your cams are independent. Lowering both lobe centers does two things.

1. Advances the intake cam's open / close point. That, done by itself would raise your cylinder pressure because the intake valve would be closed for more of the compression stroke.

2. Retards the exhaust cam. In combination with the advanced intake cam, puts more TDC overlap lift on both sides into the setup. More TDC overlap lift will narrow the power band to some extent.

It generally takes about 4 degrees of cam timing change on a mildly tuned Z to provide any real noticeable difference you feel in the seat of your pants.

You want a setup that will put more bottom into the motor on that thing. 104 /108 will do that. That's 104 on the intake with 108 on the exhaust. That's advancing your intake 1 and advancing the exhaust 3.

Again, my setup is not a drag racing bike, unleaded pump gas with a little more low to mid range zip... Nothing outrageous here, just a strong running motor...

OMR

my head is starting to hurt here guys!:blink: :laugh:

PLUMMEN wrote:

my head is starting to hurt here guys!:blink: :laugh:

Probably still hung over from the ChiaPet thread. :laugh:

#417 people have viewed this post. #30 times people have posted stuff on the subject. It must be a complex subject. I haven't seen any big dogs jump in to set everyone stright, to tell us how it really is or why it's been done. Why?

I find reading cam articles or cam timing articles to be very dry and boring at best. They make MY head hurt and I sometime want to tear out my own eyeballs! Like I said before "those who know,don't say". Those that try to find the answers are met with resistance. Possibly, those secerts makes some guys a lot faster then others.......

I hope this thread is kept alive as a group learning project for everyones betterment.

Why hasn't anyone answered my question on the characteristics of the cam timing I posted? I'm not the only dope out here asking these questions.

417 people gave it a look and only 30 took the risk to speak-up!

one of the reasons i don't normally worry about being too crazy about what is the right cam timing is simply that i don't care who you are no 2 engines you build will respond the same way to a set cam timing profile if you put 2 identicle engines on the dyno you would be hard pressed for them to make excactly the same power. i try to give the engine what it wants there are many varibles involved;pipe diameter, primary tube lentgh, collecter size, carb size and set-up, filters or none,velocity stacks and lentgh, jetting ignition timing,type of fuel,even down to what type of oil you are running also a lot of people get hung up on trying to make a differance in the little things unless you have unlimited timeon engine or chassis dynos and unlimited partsupply the only real way to find out weather somethings gonna work is by the seat of the pants or on a dragstrip and since most people arent drag racers that is not an option for most people that leaves the seat of the pant's so what i say is set to the cam companies specs enjoy the ride because alot smarter men then me designed these product in the first place

Very well said Timebomb!

Alot of old engine buiders say "when you find the cam you think you need,then buy the next size smaller" I have found this true for me and others that I know. I try to always keep it in the back of my mind. I tell others when the bike is tuned to 100% and the rider is tuned to 100%. Then buy bigger cams!

I am not an expert . this is from info I have read and learned.


Overlap
The amount of overlap, between the intake opening and the exhaust closing, and where it occurs, is one of the most critical points in the engine cycle.

This overlap phase, is very critical to vacuum, throttle response, and, gas mileage.
Remember this when u add bigger carbs. More overlap = less vacuum response. Smaller carbs require less vacuum response.

More overlap will lower cyl pressure at low rpms . Beneficial for preventing detonation.

The exhaust stroke of the piston has pushed out just about all of the spent charge and as the piston approaches the top and the intake valve begins to open slowly, there begins a siphon or "scavenge" effect in the chamber. The rush of the gases out into the exhaust port will PULL in the start of the intake charge. This is how the engine flushes out all of the used charge. Even some of the new gases escape into the exhaust.
If the overlap phase occurs too early, it will create an overly rich condition in the exhaust port, severely hurting the gas mileage.

ADVANCING the intake and RETARDING the exhaust (“closing up the centers”) increases overlap and should move the power up in the RPM range, usually at the sacrifice of bottom end power. The result would be lower numerical values on both intake and exhaust lobe centers.

RETARDING the intake and ADVANCING the exhaust (“spreading the centers”) decreases overlap and should result in a wider
power band at the sacrifice of some top end power. This condition would be indicated by higher numerical values on both intake and exhaust lobe centers. By moving only one cam the results are less predictable, but usually it is the intake that is moved to change power characteristics since small changes here seem to have a greater effect.


the intake opening.
If the intake valve opens too early, it will push the new charge into the intake manifold. If it occurs too late, it will lean out the cylinder and hinder the performance.

the intake closing.
This occurs slightly after Bottom Dead Center.
The quicker it closes, the more cylinder pressure the engine will develop, creating more torque.
but, make sure that you hold the valve open long enough to properly fill the chamber,or u lose power.

The longer the intake valve stays open past bdc, u will get a inertia effect if the rpms are HIGH enough. As the incoming charge picks up speed it cant stop fast enough, and it will over stuff the cyl at high rpm. Remember the piston almost stops at bdc as it changes direction. but it will loose charge at low rpm. This is , due to the piston coming up and pushing the charge back out the intake, if the charge is moving tooo slow to create enough inertia to keep itself moving downward.
Therefore, delaying intake closing will move your power up or down the rpm curve.

The exhaust stroke.
Once the piston passes through Top Dead Center and starts back down, the intake charge is being pulled in quickly so the exhaust valve must close at precisely the right point after the top to keep any burnt gas from reentering.

The exhaust closing

If the exhaust valve closes too early it will trap some of the spent gases in the combustion chamber, diluting the next charge.

closes too late
if it closes too late it will over-scavenge the chamber; taking out too much of the charge, again creating an artificially lean condition


OK, Now what do we do with all this info??
Well for me, its just a tool.
As we know the motor is the sum of all the parts. Most importantly they must work together towards a common goal.
As we change parts we always compromise something.
As we add bigger carbs, header, bigger cams, we move the power up the rpm scale.
All of this means less bottom end.
Just a header or carb choice is a big change.
A header itself will cause reversion if not fitted to your other parts properly.
A large carb will move the power up dramatically at the expense of the bottom end response. This is where fuel injection saved the day.
As u can see the motor is affected in many ways.
I don’t expect changing the cam timing to be a cure for the wrong cam.

If u feel a massive dif after degreeing , maybe u have some wrong components in the motor.
Every timing change has a compromise somewhere. New motors have veriable timing to make the best of things.
Moto GP bikes have GPS’s talking to the timing computers and making adjustments for every turn on a given track.

All we can do is pick the cam for the characteristics that we want, and then fine tune it a bit to work with the other components we already have by degreeing.
I think u need to look at your motors week spot and tailor your cam timing to enhance that spot.
If u look at a dyno chart of a motor and see a slight flat spot at say, 5000 rpm u could adjust the cam timing to help fill that spot.
I think the best power curve would be 1 that climbs steadily. Not 1 where u feel the cams kick it hard at 1 particular rpm. This is best for a street ride IMO.A drag bike would be dif.
This is a big subject. All u really need to do is look for your motors weakness and figure out witch way to degree it,to help it. If that isn’t enough, then u need a dif component.
Weather that is a dif cam, carb, or pipe.
I hope this is of some help.
My fingers are tired now by.

Just to let you all know, I've requested this posting be removed...

Seems the title and wording I used in the document is offensive to some of our members so no big deal, have it removed...

Please start another CAM degreeing post to continue the discussions...

OMR