valve adjustments

[gary newton]

The base circle is the part of the cam lobe that is round like a half circle. It is opposite of the tapered side that actually opens the valve. I'll see if I can find an illustration.


Can't seem to upload the picture from PPT. Let me know if the explanation doesn't work for you.

[tool]

Originally posted by jjames2
Perhaps I know this under a different term or I don't know it at all, but what do you mean when you say "the base circle of the cams is contacting the followers."?

-The base circle is what the majority of the cam profile is comprised of. The part that does all the work is the lobe. It's an expression I heard in the machine tool trade 25 years ago and it stuck in my head for some reason. It may not be what everybody else calls it so if there's any confusion about this it's just me.

[gary newton]

Originally posted by tool
-The base circle is what the majority of the cam profile is comprised of. The part that does all the work is the lobe. It's an expression I heard in the machine tool trade 25 years ago and it stuck in my head for some reason. It may not be what everybody else calls it so if there's any confusion about this it's just me.

That is what I have always heard it called. I think you are correct in calling it the Base Circle.

[jjames2]

Got it. Thanks for the clarification.

[motorcitycobra]

... for all these detailled explanations!

Bought my 12 REX in summer 2006 with 12,000 kms on the clock from a dealer. Service + valve clearance check was done. Have gone 16,000 kms til August 2007 so clock said 28,000 km.

Brought be bike to the dealer for valve clearance checking; they explained to me that they need to drain the coolant, remove the system and so on ... ... so of course it was expensive.

Further, they placed the coolant hose in wrong position over the ignition cable to the second spark plug so I had trouble at spark change.

Before this, I did anything myself except the valve clearance measurement and the carburettor adjustment (when necessary). Due to my experiences with the so called expert mechanics at the dealers I´ll ANYTHING anytime myself.

Therefore, the detailled information here a highly appreciated. #

Thank you guys!!!

[tool]

Adjusting the valve clearance is a fairly easy job to do once you've seen it done before. I was a bit reluctant to do mine the first time and I've been around precision machining for over 25 years. Having done mine several times I don't think twice about doing it now, you won't either after a couple of times. At one mod party there were three or four bikes that were finished in about 3 hours from start to finish. The ony thing that will hold you up is having shims on hand to replace so maybe you'd want to consider having a shim set on hand. Inviting some friends over to help also helps the job go smoother. I fully encourage you to attempt doing your own work on the Rex. Any questions can be posted here that will get a quick response. This is a good board with lots of helpful people that are willing to share what they know with you. If you have any mechanical skill then go for it. Do a search for any job you're contemplating as there's probably been a write up (some with photos) on it already to use as a guide.

[sillyhillbilly]

You never remove the cams to do a valve adjustment. In fact, you could not do it properly with the cams removed. Don't take your bike to either one of those shops for ANY service.


TG

i would have to disagree with that statement about removing cams
because i do pull my cams, my overgrown fingers just dont fit in there to get the shims out or in, and after way too many problems trying it that way, i dont anymore, I can pull cams and put them back in in 15 minutes, and yes i know thats time it doesnt take others, however its quicker than pulling an oil pan looking for a shim.

[sillyhillbilly]

The roker arms are spring loaded and slide out of the way so that you can chnage the shims without removing the camshafts.

The shop that told you they had to remove the cams don't know the setup of a rex.

Here is an amatuers description of how to do it (in other words what I did)......

"The rex was getting a bit tickety, so it was about time to check the valve clearances. I suppose you should have this done every 10,000km or so, but mine had not been checked for a bit longer than that. I know, I’ve been a naughty boy and I apologised to my bike for that.

First thing to organise with valve clearances is to make sure you have all the bits necessary. The workshop manual is a great help in providing not only the clearance specs, but also the tools you may need. The bike should also be cold (room temperature according to the manual) before you start the adjustments.

I already had a set of feeler gauges, but a longer set would have been more helpful. Some of the gaps I had to measure were very hard to get to.

Other tools required included:
A 15/16ths spanner to turn the crank and position the cam lobes.
The obligatory 10mm socket.
Numerous other spanners/sockets.
Allen keys.
A couple of small, flat blade screwdrivers and a phillips head screwdriver to undo the coolant line hose clamps.

As you have to remove the timing cover to rotate the crank, I decided to perform an oil and filter change as well. Oil was $30 and the filter $12. If you change the oil, you’ll need a 17mm spanner too!

The timing cover spans the join of the upper and lower crankcases plus there is a rubber grommet in the lower crankcase that allows the electrics to get in. Each of these three areas have to be sealed with an RTV gasket sealant as well as the gasket. Nine dollars at Supercheap saw a new tube and I already had a timing cover gasket.

I also purchased two other tools that were invaluable. A set of digital, vernier callipers ($35) and a magnetic pickup tool ($10). The callipers allowed me to measure the thickness of the shims when there marking had been worn off and the magnetic pickup tool allowed me to remove the shims and to fish out any shims that were inevitably dropped in the process of replacement.

The ZRX runs 9.48mm shims under the rockers so a selection of shims were required. Fortunately, I scored a set of 22 shims, off eBay, for $60. Considering that I was charged $17.50 a shim last time it was serviced, that’s not too bad! You can reuse the shims, so all up I had 28 on hand. Total outlay = $156



First thing I did was remove the fuel tank then drain the coolant and the oil. I only changed the coolant a month ago, so that was emptied into a clean bucket and stored. The oil was disposed of at the local recycling plant.



Then you pull the spark plug leads and tuck them out of the way. Then the thermostat housing and associated plumbing was removed along with the KLEEN paraphernalia that exists there. (Of course it is still on my bike even though I’m running pods!)



The next thing to remove is the baffle behind the cooling fan. Some people miss this and it is a constant source of frustration. It is actually bolted to the rocker cover but the bolt is hard to see. If you neglect to unbolt it, you can move the rocker cover up and down and achieve a little sideways movement, but you can’t get the beggar out!



Once all that is removed, you can slide out the rocker cover and reveal the valve gear. Be careful as you do this as there are gaskets around the spark plug holes that need to be kept in good condition so that they can be re-used.





Next step is to remove the timing cover. I have mine bolted on with 5mm allen head bolts but the norm is a standard 8mm bolt. Once this is removed, carefully remove the old gasket and sealant from both surfaces (this can be done later). Removing this cover reveals a large nut that is on the end of the crankshaft. This in turn is connected to the cam gear via a hivo chain running up the side of the engine.



In order to rotate the crankshaft easily, compression in the cylinders should be alleviated, so whip out the spark plugs. Make sure you block the spark plug holes with some old rag to stop any errant shims dropping down into the cylinder! Once there is no compression, the crank can be easily turned by hand using the 15/16th spanner.



The service manual tells you to line up the mark on the ignition rotor with the mark on the inside of the crankcase. This, however, had the cam lobe still placing pressure on the rocker and, thus, there was no clearance between the rocker and the shim! Enter my mate Steve the engine guru!

His advice was that the cam lobes should not be putting pressure on the rockers and that if they were, then just rotate the crank until they don’t. fair enough… Onward and upward!

Kawasaki have blessed the ZRX with rocker gear the are spring loaded and slide out of the way for adjustment. This eradicates the need to remove the cams and makes life a whole lot easier.

At this point, the engine must be stone cold to get good results. Measure and record the clearance between the valve shim and rocker arm for all the valves and write the millimetre clearance on a valve clearance diagram (VCD) like the one below.



Remove each valve shim and write it's size on the VCD by the clearance. This is where the magnetic pickup tool came into its own!. Remember, the rocker arms are spring loaded horizontally, so just slide them over and out of the way. (You may need to use a thin, flat bladed screwdriver to get the rockers out of the way – especially if you have fat fingers – so be careful not to score the cam lobes) When the shim is removed, let the rockers snap back into place temporarily. You'll find most of the shims have a size marked on them, but some will be unreadable. Measure these with a micrometer or callipers and record the size on the VCD.



Using the service manual and the chart therein, select the shim size needed. The explanation on how to use the chart is very good in the manual and once you've done a couple it will seem easy!

Write the shim size needed next to each valve on the VCD. You'll probably be able to move some of the shim you have to the locations you need that size, so purchase of a new shim for every tight valve is not usually necessary.

Carefully install the new shims and check the clearance to verify in tolerance. If you did everything right, it will be. If you drop any shims, and you will, use the magnetic pick up tool to retrieve them. Steve and I “modified a small flat blade screw driver to aid in the installation of the new shims.



That and a little dab of grease allowed us to place the shims neatly in their holes with a minimal amount of swearing. At this point it was also agreed that a hands free, head lamp would be a useful addition to the tool kit!



When all are in spec, slide each rocker arm over and coat the shim and rocker arm contact points with a small amount of "moly" grease. This will cost about bugger all at the auto parts and you'll have enough to do this 50,000 times!

Put it back together. Do the valve cover first, so if anything get dropped into the chain gallery it's easily retrieved.

Put silicone where indicated on the crankcase and install the timing cover. Note that 2 of the bolts of the timing cover, indicated in the manual at 10:00 and 11:00, go into oil passages, so the threads must be coated with a thread locking compound/sealer. Pick the non-hardening kind from the auto parts.

Remember to re-install the oil drain bolt, filter and filter housing and fill her up with oil.

Put all the hoses on TIGHT, let them sit overnight and retighten, then fill up with coolant and bleed the cooling system.

Initially I was a bit apprehensive about performing this task, but, now that I have done it, I’d do it again in a second! Having Steve there certainly gave me more confidence at the start, but by the end of the exercise, I was more than confident in my abilities to perform the task myself, unaided.

The last time I had the valves checked, and the oil changed, it cost me close to $500. I also was without the bike for 10 days as the correct shims had to be ordered. This time I have spent well under $200 on parts (and that bought me some tools too!) and have basically done al the work myself. Steve’s labour comes cheap. A few beers/bourbons and a couple of home cooked meals see’s him happy. Plus he’s a lot happier tinkering on bikes rather than the big diesels he normally works on.

A lot has to be said for the 6 “P”s. Prior Preparation Prevents Piss Poor Performance. After reading the manual, consulting the ZRX owners website and talking to Steve, I was pretty well versed on what to expect. I also made sure that I had everything I needed before I started the job. The whole job has probaly taken me between 7 – 10 hours of pottering around and not rushing it."

Cheers,
Pete

P.S. Since doing this, some of the guys rekon you don't have to drain the coolant, and they are correct, but if you want to change it, now is the time.

nice write up, now tell me where does it say to use that non nut on the crank to rotate it?
you know it can lead to misalignment of the timeing rotor?
that nut isnt a nut, its an glorfied washer that does engage the locator pin of the pulse rotor?
its only a nut shape so one can put an backing wrench on it while tightening the allen head bolt that holds the timing rotor on?

[Dave in WI]

nice write up, now tell me where does it say to use that non nut on the crank to rotate it?
you know it can lead to misalignment of the timeing rotor?
that nut isnt a nut, its an glorfied washer that does engage the locator pin of the pulse rotor?
its only a nut shape so one can put an backing wrench on it while tightening the allen head bolt that holds the timing rotor on?

Yes I'm replying to a years-old post...

I had to look this up in the shop manual, on page 4-21 it implies that you should use this nut to turn the engine, but it doesn't actually say how to turn it. A diagram shows the nut with an arrow for the direction of rotation, but does not actually show a wrench on the nut or tell you how to turn the engine.

I think putting the bike in gear and using the rear wheel to turn the engine is a safer bet.

[Victour]

I wasn't going to drain any coolant, but the heat shield cover was hard to get the bolt and remove and install .. So I removed the top Rad.. Hose after draining 1 qt. of antifreeze.. Made it simple.. Removed valve cover slipped right out on #4 side... then I had the diagram of 4 cylinder with 4 valves.. I started on #4 cylinder easiest one to get too just make sure the lobes are pointing slightly forward.. and UP..Check the clearance and find a shim to install.. Slide Rocker over lock on valve retainer.. used small screwdriver to bump shim loose. then a magnet on a Screw starter to remove the Shim.. then used grease on a bent and flattened clothes hanger wire. this made it easy to get the shim straight where it would almost fall in the hole.. I would rotate it with the hanger, flip the Rocker over then go to the next one after marking the paper. also I could see grease on the valve retainer knowing I had done this one I used the Rear wheel to rotate to the next one, I think I could do 4 valves which mean't I had to rotate 4 times, Friends still complain I have a noisy valve train.. I think it is the Chain.. You can't drop a shim in the engine except the big Hole at the cam chain.. that also makes #1 exhaust very hard to do. Not much room.. But the coat hanger wire bent a little different allow me to do this just fine.. Just saying... Don't be afraid.. Tell the stealer to get lost.. Unless you need parts..

[kawafastzrxer]

cheapest place ive found to get the shims was at the local honda dealer 3.00 a pop,MAMA KAW 9.00 a pop.