ZX-12R Valve Clearance Check
and Adjustment Procedure
This Write-Up has been prepared and written by Blitz' - of ZX-12R.org
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Before we get started, a few things:
1) I strongly recommend you do not attempt this procedure without a factory service manual.
If you own the bike, you should own the manual.
2) This is not a procedure for those lacking in mechanical aptitude.
You can really screw your motor up if you do this wrong and/or get careless.
That being said if you are mechanically competent, thorough and can follow directions, you can do this procedure.
3) If you do this procedure you are going to save yourself a boatload of money vs. having the dealer do it.
Donít be afraid to spend some of that money on some good quality tools you will need to do the job properly.
4) I believe in saving myself frustration by making my work easy to get to.
If you want to ďsave timeĒ by not removing certain items (like the radiator) have at it.
Iíve done the valves on numerous 12ís and the 15 minutes it takes to remove peripherals,
is more than made up in time saved/knuckle skin when you get down to the job at hand.
Besides, your coolant needs to be changed anyway if you are like 95% of the people reading this. ;)
5) There is no need to drop the front of the motor to do this procedure however, it is tight IF you donít have an air ratchet.
A Word of Warning
Make sure the 'dowels' don't drop out of the rocker cover, into the engine.
What tools and equipment will you need to do this?:
1) A good set of feeler gauges. It helps to have both shorties and the larger angled ones,
because some of the cam lobes are harder to get at with one or the other.
2) A good set of Phillips screwdrivers.
3) A good metric socket set.
4) A good set of metric box-end wrenches.
5) A good micrometer or vernier caliper. Often the size markings on shims are not readable,
so you have to measure them to determine the correct replacement shim.
6) A couple of baggies
7) A Sharpie (permanent marker)
8) Blue or green 3M painters masking tape (stands out Ė Blue is my favorite)
9) A roll of paper towels
10) A torque wrench
11) And of course, youíll either need to shell out $7 per shim at the local stealership,
and wait for them to come in, or do what I do and spend $70 and get a complete shim kit from these guys
http://www.cyclebuy.com/shopping/hotcams/shimkits_948.htm for the United States
Update: Valve Shim Kits or individual Valve Shims are readily available
from eBay, Amazon and lots of websites.
Valve Shim diameter 9.48mm
The shim kit is definitely the way to go.
What tools and equipment will make this job a lot easier?:
1) A compressor and an air ratchet are a Godsend on this procedure because the clearance between the head and ram air box is tight.
An air ratchet makes removing the cam holder bolts infinitely easier. If you donít have these, borrow them.
You will thank me for that advice after you are done.
There are several things I have learned over the years that a manual wonít point out to you. Also, itís not uncommon that a manual will
completely skip a step that can really save time. Ergo: itís technically NOT required, but can really save time.
I will never recommend anything that does not follow
but I will recommend things that I feel make the procedure easier or better.
These procedures are written off of the A model.
The B model is very similar but there are some mostly visual non-mechanical differences youíll need to take into account.
For instance the plastic on the B model is slightly different, the valve clearances are different (if I remember correctly), etcÖ.
Just keep that in mind as you go through the procedure/pictures.
That being said lets do it.
Prepping the bike:
Remove the necessary plastic:
a) Remove both lower fairings and the inner fairings (behind front wheel.
b) Remove the tank skin. This is required to remove the ram air ducts.
c) Remove the ram-air duct covers and duct work between the fairing and frame.
Label every connector on the left side of the bike with a Sharpie and painters tape.
Most of the connectors are obvious, but this will save you time when you put everything back together.
I label mine #1 / #1 on both sides of connectors, #2 / #2 and so on.
There are some connectors on the zx-12r (A model TPS and another one) that come to mind that are identical
and will cause you great pain and strife trying to figure out what you screwed up if you cross them.
Remove the heat baffle from the right cylinder bank by pulling the X-mas tree plug (inset).
This heat baffle is prone to heat damage so when you remove it, thoroughly spray it with Armor All and set it aside.
Remove the bracket on the cylinder bank that holds the clutch cable.
This is the bracket that the X-mas tree above was pushed into (look for the 10mm bolt in the inset picture above).
This will allow you to move the clutch cable out of the way.
Unplug all of the electrical connectors on the left side of the motor.
The horns, temp sensor and fan feed will have to be disconnected to remove the radiator.
Drain the radiator. The easiest way to drain the coolant on a 12 is the bleed screw on the lower part of the water pump.
Itís the one located at 6 oíclock on the water pump and listed as ďDrain BoltĒ in the cooling flow chart of the manual.
Undo that screw and remove the radiator cap. Have a pan ready when you remove the radiator cap.
The coolant will shoot out with vigor.
Disconnect all of the radiator hoses and remove the radiator. Tape them and mark them before you remove them.
Use care Ė the radiator fins are super fragile.
Remove the overflow reservoir from the left side of the bike.
Move the upper radiator hose (on right side of the motor) out of the way (towards the back of the bike).
Secure it with a zip tie or string.
On A model bikes, remove the upper-upper motor mount bolts.
The composite cover on top of the valve cover is almost impossible to remove (without breaking)
without moving the upper motor mounts down and out of the way.
You donít have to support the motor Ė the rear mounts will hold it in place.
Itís $60 at Ayers if you donít do this step and break it.
Donít ask me how I know.
Remove the rubber insulator pad from the composite cover on the top of the valve cover and remove the composite cover.
There are two mounting screws on each side towards the front that hook to the ram air and two 10mm bolts on top.
The yellow circle is the left side screws mounting to the ram air assembly.
Remove the stick coils. Take your time here:
a) Remove the power/ground plug from each stick coil carefully. The retainer clips will break if you force them.
After all four plugs are removed carefully pull their lead wires away from the molded tab retainers in the composite
cover out the left side of the bike to get them out of your way.
b) Remove the stick coils. Donít force them. Gently twist them back and forth while giving a slight upward pressure.
Theyíll come out.
If you are going to change the spark plugs, now is the time to stick a blow tool down into each sparkplug hole and blow out
any junk that has built up next to the plugs. There should be minimal contamination as the stick coil boots are a tight fit,
but better safe than sorry.
Remove the valve cover. Be careful Ė the valve cover bolts have a very shallow heads and are easily stripped.
Remove the timing sensor cover.
Position the crankshaft at TDC for cylinders #1 & 4. The crankcase mating line is the timing mark
Ensure the camshaft sprockets are lined up with the ď320Ē marking on top and,
The IN----EX----IN----EX markings upright. If they are not, rotate the crankshaft another 360 degrees (lining up the TDC - #1 & 4 mark again.
Check the valve clearance following the instructions in the manual to the letter.
Basically you are going to be checking half of the valves and then rotating the crankshaft 360į and checking the other half.
Record the clearance for each valve using the template at the end of this document.
The first time you do this, triple check your measurements.
A much smarter man than me (my Grandfather - who is a master woodworker),
once told me measure twice and cut once. Itís good advice.
Hereís a little trick I use to speed up reassembly and make it totally obvious where everything needs to go on reassembly.
Do this AFTER you have finished checking all clearances.
Clean the sprockets and cam chain with a paper towel and then scribe a line completely across both camshaft sprockets
and the chain with a Sharpie. On the cam chain circle both rivet heads above and below the scribed line.
Mark an X on the top of each sprocket.
The white paint marks you see are the factories way of accomplishing this when your motor was assembled.
This is a conceptual of what we are trying to accomplish:
This is an actual of what we are trying to accomplish. Pretty doesnít matter, accuracy does.
The whole goal is you want to put everything back together just like you took it apart.
After you do this procedure a couple of times this isnít necessary but the first time around itís great reassurance for you.
After you have recorded all clearances, if you have any out of spec, remove the cam chain tensioner and camshaft cap bolts.
I put a small socket wrench on here to indicate a cap bolt, but I use an air ratchet. Much easierÖ..
Loosen the bolts slightly working around
the entire holder.
but I think itís easier on the holder because you are spreading the torque load as loosen the bolts.
Sort of a reverse torque pattern if you will.
The cam holder cap bolts are NOT all the same. I use a cardboard template to keep everything straight as I pull the bolts:
When you remove the camshafts, keep the cam chain from slacking on the crankshaft,
so that your scribe marks can be used to put everything back in place.
Stuff paper towels in ALL crevices at this point. This includes in the camshaft chain valley,
in the open areas around the spark plug holes, etc..
Basically any open area around the shim buckets.
If you drop a shim (they are slick and hard to hold) down into the motor you are going to be hating life in a major way.
Pull the shim bucket and shim for each valve that is out of spec.
Do this one valve at a time working from the front left (#1 exhaust valves) to the right (#4 exhaust valves)
and from the back right (#4 intake valves) to the left (#1 intake valves).
The order is not random, itís organizational.
Use a magnetic pickup tool to lift the shim bucket and shim.
Measure the shim size if itís not clearly readable (70% arenít),
write the size down on the template and place that shim and bucket in the proper position on the template.
Take care here.
It is very important that you keep organized and keep the shim where it belongs on the template.
Now that you have measured the shims for all valves that are out of clearance,
use the adjustment charts in the manual to determine what size new shim you need.
Valve clearance on a shim and bucket type valve train DECREASES with wear, so normally you will find you are putting in a thinner shim.
This is an example of the template I used that was hand written.
Youíll see the clearance noted for each valve (ex: .25 mm), the shim size (ex: 245) noted on the valves that were out,
and the shim(s) and bucket for each.
If a given valve is right at the spec limit on the loose side, I leave it alone as it will tighten up as wear occurs.
Okay, now that you have determined the correct shim for each out of spec valve,
carefully place it on top of the valve in the relief.
I put a dab of grease on each relief to hold the shim in place.
Be absolutely positive the shim is fully seated. If you screw this up you will grenade the motor.
After you put each shim in, carefully replace the bucket and seat it.
Replace the camshafts (noting IN for Intake and EX for Exhaust) lining up all the timing and scribe marks.
Place the cam holder on top of the camshafts and replace each cam holder bolt into itís respective hole.
Slowly tighten the cam holder bolts rotating around the cam holder.
While you do this, you need to keep slight tension on the cam chain as it will want to jump around as the cams are pushed down.
Use a friends finger, a dowel, whatever. I prefer a finger because it can feel and react as the tension increases.
This is, IMO the trickiest part of this procedure. Take your time and move slowly.
It is very easy for the cam chain to jump a tooth so youíve really got to watch everything as you do this.
If youíve gotten the cam holder bolts all snugged up and your timing sensor and cam sprocket marks are all lined up correctly, you are home free.
Torque the cam holder bolts to their proper specification.
Install the cam chain tensioner noting that you fully compress it and then move it out 3 clicks.
It will adjust itself automatically when the motor is started.
Triple check that all of your timing/scribe marks are correct before you start to put everything back together.
Reinstall everything in the reverse order you took it off.
I recommend reconnecting the wires after you have the valve cover on,
and starting the bike for just a few seconds to ensure you didnít screw anything up.
A bike that has the timing off will not start normally and will sound like crap when it does.
If this happens, stop the motor immediately and determine what is wrong.
The A model timing marks do not line up in an absolute straight line across the cylinder head,
so the lineís you scribed with a Sharpie in step 19 can make an excellent secondary check.
Youíll want to note that once you rotate the motor the cam chain pins you circled will no longer line up.
I rotated a motor once to see how many crank rotations it would take to line them up again, and gave up at something like 19. J
After you are all done, pat yourself on the back, drink a cold beer and smile knowing that you just saved yourself several hundred dollars.