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How to degree cams, 96 750 GSXR

22K views 24 replies 13 participants last post by  12345hendrix 
#1 ·
FIRST, there will be several posts as, i write, please DON'T hesitate comment or post until I say I am done.
This is not overly complicated, but it takes some intellect, and basically mechanical competency. If you can adjust and shim your valves, and have access to the tools necessary to do this, it is reasonable that you can successfully do this.
It is easiest done with the motor removed from the frame, but I have most often done it with it installed in rolling frame.
I use a Hot cams kit, but all you need is something to thread into the spark plug hole to find tdc, a degree wheel, and a dial indicator with some versatility.
The cams I was degreeing were ones that I had bought, never used, sold to Sleeper750, and had sent back to me my WILLIAMHBONNEY. They are stock cams with APE slotted cam sprockets and press on carriers installed. ***It is important to note that if you are installing cams with non-stock profiles, you should follow the mfg install notes, and likely not install by lobe center timing.
So...... Assuming that you have uncovered your motor, lets take the valve cover off, and remove the timing plug and the small round cover over the right hand side of the crankshaft so we can turn the motor with a 14mm socket.
Let's take the spark plugs out so that we don't have any compression to overcome.
Then, we turn the motor in the forward direction until the timing mark lines up, and the marks on the cams indicate that 1 and 4 are at tdc.


#3 should be pointing up, reasonably vertically on the intake cam, and #2 should be doing the same on the exhaust cam. There should be 15 pins on the cam chain including the ones on the arrows, between the arrows.
****Refer to these criteria upon reinstall on cams for timing.
At this point I placed my replacement cams over the stock cams to verify that the adapters had been pressed on in appropriate locations and that the sprockets were timed accordingly.
I then did a quick valve lash check, as this motor was the subject of a exhausting top end rebuild a year or two ago, and the valves were bench shimmed after the head came back from APE with a full radius valve job, and considerable seat material cut away. The motor was then broken in on the track in expert level sessions for 2.25 track days until the big crash. Close inspection revealed four valves that would need reshimming, which I did while the cams were being swapped.
 
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#2 ·
So, remove cam chain tensioner (in this case and APE manual one.. (MCCT))
No reason to back off tensioner bolt in this case, just back out two screws holding tensioner in place and slide it back.

Now remove the top cam chain guide.
Remove the oil tube connecting the two cam towers.
Following the numbered sequence stamped on the cam towers, slowly loosen the cam tower bolts in stages, a couple of turns at a time, to slowly let it rise in stages. Do the same with both caps.
Remove the caps, make sure you don't loose the two guide pins in the each cap.
Lift each cam out, keeping tension on the cam chain, and make sure you don't loose the c-rings that sit in the bottom bearing race.
Zip tie or use one of APOKS little bungee to tie off cam chain to keep it from looping under crank gear.
***Here is where I swapped shims under buckets

You would then press off the stock cam sprockets and press on the carriers, mine were already installed.
Now, coat all the cam journals with assembly lube

Reinstall cams, making sure they locked into c-rings, set your timing as per the first post, zip tie cam chain to cam sprockets and tighten down cam towers according to numbered sequence in stages, to 88 in lbs. Recheck timing marks, install cam chain tensioner, cut zip ties, and install upper guide. Install oil passage after we are done degreeing cams, as it gets in the way.
 
#3 ·
OK, ready to degree? I set up my degree wheel on the left side of the motor, attaching it to the bolt holding the stator rotor on the crankshaft with a small spacer underneath. Usually you attach it to the LH side, but it's a little awkward on a srad.

Next thing is to fabricate a pointer, out of wire, and attach it to the motor.
Since you have it timed at tdc for 1 and 4,according to the timing marks, set your pointer and wheel to TDC.
We are going to find true TDC now, using positive stop method :
Rotate your motor forward 90*

Insert stop into #4 spark plug hole

Now rotate motor backward until piston reaches stop, *record number
Rotate motor forward until it touches stop again, *record number
Now, add both numbers together, divide by two, and move your pointer to that number.
In my case 49+46=95/2=47.5
TDC is now in the middle, verify by rotating motor both directions and it should stop on the same #, in my case 47.5
 
#4 ·
Now, set up your dial indicator, usually on a magnetic base, so you need to fabricate a piece of steel that you can bolt to the towers.
Let me digress a little, regarding numbers. We are going to degree by lobe center method. Lobe center is measurement taken at. 0050 lift opening and closing. I picked my numbers off of past experience, but it also agrees with what is published on Factory Pro website. Not not arbitrarily choose degree numbers, you may be disappointed. You may lunch a motor. PTV clearance is critical.
Also, I measured stock lobe centers, before I took anything apart, and came up with 113* intake, and 107.5 exhaust. My goal is to reach 105 intake and 102 exhaust.
I placed my plate on the towers and bolted it in place, and set up dial indicator, making a longer tip out of a heavy guage coat hanger. It is imperative that you set it up with the dial indicator in line with the valve stem to minimize it walking around during bucket depression.
When you think you have it set up, zero out your dial face, rotate the motor and few times and make sure you dial always returns to zero..... Odds are it won't without a few adjustments.


Once you have it set up, SLOWLY turn motor forward until dial begins to move, stop on... 0050, and record number on degree wheel.
In this case 20

Now keep rotating it slowly as it opens fully, then stop it on the same. 0050 as it cases and record the number... In this case 50.
Now for the math:
Opening BTDC+closing ATDC +180/divided by 2 minus the smaller number = LC
SO..... 20+50+180/2=125
125-20=105LC
If this isn't what you want, loosen one cam bolt, rotate crank, loosen the other bolt, and turn
crank a little, then tighten one bolt.
Remeasure.
On intake cams, for smaller lobe centers, roll motor backward. Roll motor forward for larger LC.
It took me three tries to hit 105.
When you hit it, roll motor around to loose cam sprocket bolt, remove it, and reinstall with blue loctite, roll motor forward to other bolt, do the same.
 
#5 ·
Move your setup to the exhaust cam, repeat the process
Opening BBDC+ CLOSING ATDC+180/2-Smaller number
Here I went from 97 to 102 in three steps, getting
16+40+180/2=118
118-16=102LC
For smaller lobe centers on exhaust cams rotate motor forward, for larger lobe centers roll motor backward (opposite of intake cam)
Add your two lobe centers together gives you lobe center separation. Smaller numbers generally give you more midrange, larger give you more top end.
Now check PTV clearance
Check for 1 mm clearance at 15 degrees BTDC for exhaust cams and 15 degrees ATDC intake cams.
Rotate degree wheel to mark

Depress bucket with screwdriver and watch dial guage, looking for at minimum 1mm movement available.

Now, button everything up, double check all your timing, bolts, torque...... Done.
I could have forgot something, let me know...
Done.
 
#6 ·
That's an awesome job! I'm going to have to read through 10 more times to wrap my head around it. Really appreciate your effort and expertise!
 
#7 ·
One thing to remember, if there is a doubt, rotate the motor again and check your numbers!

Great write up!
 
#9 ·
nice write up.

you have not accounted for the valve lash in your measurements.

the maths you use will indeed arrive at the correct timing

but if it is 50thou + 4 thou lash then the duration figures are not comparable with industry standards

Industry standards measure duration at 50thou lift with zero lash.

this means that one camshaft can be reasonably compared with another.

I also notice the dial indicator shaft alignment with the cam bucket.

I understand the difficulty in locating this on the bucket but idealy this should be at right angles to the surface and in line with its travel. this will give the most accurate representation of the timing.














another method not commonly mentioned is to have your camshafts measured on an "adcole" or more commonly on a "cam-pro" or "cam doctor".

the software accompnying these machines allows very accurate analysis of the camlobe profiles and can give "lift at degree" figures.

This process allows the user to set the engine at TDC and rotate the cam until the desired lift is achieved. this will give the simplest method of arriving at the desired lobe centre timing.

Australian residents can make use of the services of "surecam" ( surecam.com.au ) who can not only measure the cams but supply extensive information about the actual lobe profile including periods of instability it could encounter during its rev range.

surecam can also custom design lobes to suit specific applications and advise on suitable timings for a given lobe measured by them.
 
#10 ·
the timings you suggest of 102 / 105 have in my experience severely inhibited the revving of small displacement engines. with engines peaking below 7,00 rpm and being reluctant to rev freely any higher.

but this is outside the scope of this thread.

readers should not jump on the bandwagon and use figures suggested by others without fully understanding what the person has set out to achieve in setting those figures.

every person interested in gaining the best from their engines should measure the cam timing.

if possible it should be set to the manufacturers intended specs and the results evaluated before moving to another timing.

moving the inlet has a different effect to moving the exhaust and the tuner should move one at a time in measured increments and the results recorded. eventually arriving at a set of figures which offer the best results for the riders application.

opening the exhaust timing figures to values around 120 degrees will for example make the engine very revvy but may make it a dog to ride at low rpm.

there is no magic figures, its relative to the application . the rod stroke ratio and the flow capacity of the head,
 
#11 ·
^ so what are you saying? Ccms work/methods are wrong? This could get interesting.
 
#13 ·
The ring-in - nice first posting (trolololoololing?) If not let ccm finish here, he's writing it up for us simple folk who do not need to yet understand valve lash and the intricate details. Not saying you are wrong or anything, just speaking from my perspective having never seen a how to degree cams, baby steps ya know?
 
#14 ·
Ccm, can you talk about the numbers a bit as far as how they affect power through the rpm range?
 
#20 ·
Bueller?...Bueller?.. Anyone?
 
#15 ·
Couple of points here
Ringin
Lash does not matter, you will end up with a larger or smaller total number but the lobe centre is consistant with these basically symetrical cams ,try the math .

ccm when i change the timing from measured to intended say from your example of 20+50+180=250/2=125
125-20=105
ok from here its easy to
A :have pre loosened the cam bolt that ends up out of reach at tdc
B : say you want 102, (125-102=23, and vise versa, 125-23=102)
C :turn the motor till the cam is at 23, loosen the top cam bolt and turn the motor to tdc, (its only 3 deg away and go slightly beyond then turn it back ) watching to see that the cam does not move , then lock up the cam bolt , check your figures, again, but you will be within 1/2 a degree if you did it right

Another thing i do is use .030 not .050, as small cams may go beyond tdc to get to .050 lift, making the small number a negative,.... confusing,

I'm not picking holes in CCM's writeup , its great and simply explains for the beginner
 
#16 ·
Maj750, yes... I also believe Lash doesn't matter.
Your Way works too, thanks for pointing it out. I sometimes do that, but wanted to keep it simple, as anticipating the out of reach bolt and the alternative adj method only seemed to complicate things for the beginner, and that is who the write up is for, after all. I appreciate your observations.
 
#17 ·
I promise to have a proper read on my day off.can tell you now though, this is beyond me..you lost me at attaching a pointer to the motor :scratch :wtf

I need to do valve clearances first, before i even think about doing this.

One curious question though.....how do you know when need to degree your cams?
 
#19 ·
I promise to have a proper read on my day off.can tell you now though, this is beyond me..you lost me at attaching a pointer to the motor :scratch :wtf
Find TDC. Get a wire hanger and stretch it out. Find a bolt hole to use to hold it down, and loop the hanger around the bolt, screw it down against the engine. Bend and point the hanger down in front of the degree wheel.

look here

 
#18 ·
hmm we should possibly make this an every mans worst nightmare pussy.... :shifty



i mean we should make this a sticky? if it seems it would be super helpful
 
#21 ·
Lower lobe center like the ones I went with generally give you more midrange, and I answered this in the original write up when I covered adding the numbers up to get lobe center separation, and said that lower numbers give more midrange. The 750 srad is a monster at 10,500 rpm to redline, what it lacks is midrange we all know that. But, you can't use those low lobe centers effectively unless your motor breathes well, like with a full radius valve job like this one ;-)
 
#22 ·
Nice. Thx. It takes awhile for this stuff to make sense when its your first look at the process.
 
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