ZRX cam pitting and missing frame bolt

[bonester]

Did first valve adjust on ZRX today and happy to report the cams are perfect. Not a scratch or pit on them! Barely worn/run in either which is great at 22000km. It might confirm the theory of cam pitting being caused by pussing around on the bike. I have now had four bikes running with this family of engines in them- GPZ900R, ZZR1100, ZZR1200 and ZRX1200R- I ran all of the bikes hard after warming them up except the ZZR1200- I pussed it around for 3000km running it in carefully and the cams were heavily pitted at 18000km. All the others never pitted the cams at the following mileages- GPZ 128000km, ZZR11- 84000km and ZRX as above. So will continue to ride the ZRX hard- probably ride it harder than any of the others too.
A couple of valves were tight but I spent all day setting all the valves to the wide side of the specs- digital verniers help- amazing how much shims vary from the sizes printed on them. Mech guru was telling me some extra power is available setting them wide through increased compression coz valves are closed longer- valves run cooler too. I always set them wide previously anyway coz they generally tighten over time and I'd rather have some extra time up my sleeve between valve adjustments. Pretty easy on ZRX anyway. Not like GT with it's shim under bucket setup....
Found a couple of other problems though and one is of great concern, the other minor- three sparkplugs were oiled up heavily as I changed them- the valve cover wasn't screwed down very tight and I assume that the four sparkplug gaskets weren't pulled down enough. They are in new condition. The other issue I discovered was of the four engine cradle bolts on the right hand side of the bike, one was missing (!) and one looser than finger tight (!!!!!!!!!) - both on the top side behind the radiator shroud. I had a problem of tankslappers at high speed with the bike some time ago- and ended up putting in new steering head bearings (they were buggered) and wheelbearings as well as front tyre trying to get rid of speed wobble. It has largely gone, but still has a bit of a weave- maybe having tight engine cradle bolts and all of them there might help! I have taken one of the lower cradle bolts out and put it in up top so I can reassemble the bike and easily instal a new one next week when I can buy one. I have torqued them to specs and loctited them too. Kinda shits me how crap the build quality is on this bike. All sorts of shit has fallen off, cracked or rubbed against things it shouldn't have. I was thinking today there is no bike at any price that I would prefer than the ZRX, so she's staying. Will just have to persevere to keep it from falling apart.

[oldman]

The oil obviously came from the valve/cam cover being loose. If it was coming from leaky rings you would be blowing blue smoke out of the exhaust and would be running like crap. Loose bolts and nuts are common on every bike I've owned. I check them all everytime I change the oil, (2,000 miles for me) and I always find some loose. I am not familiar with the set up of your motorcycle but mine uses the engine as a stressed member of the frame and without all the bolts on the engine tight you would probably get a little flex. Locktight works good on bolts to keep them tight but I still check them. A cool brew and a Jim Beam will make all things clear. By the way interesting observation on cam pitting. If what you say is true mine will never pit. I go to red line everytime I drive.

[TopCat]

Hi Bonester,
what do you call pussying / riding hard. I had an 11 with no cam pitting, bought s/h at 7.5k, sold at 49k, now have a 12, bought at 4.5k and got cams reground at 12k.
I ride the 12 on weekend runs and am off to Tassie next week. I ride mostly in the 4-6,000 rpm bracket.
TC

[bonester]

Pussying is short shifting and not getting up into revs. Riding hard is finding redline regularly. Apparently word around the campfire that lugging engine at low revs means oil pump doesn't supply enough oil to topend. GTR1000 are about the worst for cam pitting probably coz they are the type of bike that gets pussed around.

[bonester]

Loose bolts and nuts are common on every bike I've owned. I check them all everytime I change the oil, (2,000 miles for me) and I always find some loose.

Problem with the two bolts I am referring to is that they are behind the radiator shroud and the top radiator hose. I don't think many people would remove the top rad hose and shroud to check these bolts. Worthwhile though because they are somewhat structural to holding the engine in! I'll check them next valve adjustment!

[Woof]

Hmmm.... Bought my '06 Rex new to replace my Gpz 1000 Rx about the same time I read a really interesting article by some geezer about running-in by running-hard. (The non-pussy approach to running-in!) Thought I'd try it on the Rex and it runs strong and sweet with 97 000 ks on it now (four years riding). However, the cams were pitting at the 12 000 service and were refaced and reground by Tigh Camshafts in QLD under warranty. Still perfect. However, from new I did change the oil & filter at 150 ks, 300 ks, 500 ks, 750 ks, 1000 ks, 1500 ks, 2000 ks, 2500 ks, 3000 ks & 5000 ks and then every 5000 ks from then on with a good semi-synth. The cam pitting issue is pretty common with this series of engine from the Gpz750 on through to the ZRX1200 & ZZR1200. Just gotta know about it and keep the maintenance up. Loose hardware? Ah, this is what bike ownership & care is all about: know the machine and look afer it. Kool....

[Errol]

Something I was told by my dealer when I picked the ZRX up from new, "Run the idle high rather than low".

Now I never asked why & he never offered an explanation, I proceeded to set a low idle, sounds good.

When i did my first (as oppssed to a shop during warranty period) shim check on valves I found pitted cams.

Lucky I had brand new ZZR cams sitting beside me or I would have been exceptionally pissed off.

I had asked @ every service that this matter have close attention , obviously never happened.

Now I believe it to be from a low idle, leaving the last spot to get oil (# 4 cam lobes) with bugger all supply, especially if the bike is idling, hot & on the sidestand.

I now run 1200rpm idle as oppossed to my previous 850rpm.

Just my 2cents.

[TopCat]

However, the cams were pitting at the 12 000 service and were refaced and reground by Tigh Camshafts in QLD under warranty. Kool....

..... they're the same shop that reground my cams at 12k .... just had it's service at 26k and all ok on the cam front

[Gosling1]

some great info here, thanks people. Putting together the GPZ1000RX at the moment, the cams look pretty good to me, there is 48k on the speedo - no idea if its genuine ? I'll be keeping a close eye on these once the bike starts getting ridden....

[Woof]

some great info here, thanks people. Putting together the GPZ1000RX at the moment, the cams look pretty good to me, there is 48k on the speedo - no idea if its genuine ? I'll be keeping a close eye on these once the bike starts getting ridden....

Mate, I have some experience that you may find usefull and which works for all engines pre-ZX10 (1989?)

In my pre-Rex days, I had a GPZ1000Rx bought with 25 000 k on it. At 30 000 I took the lid off and found both camshafts and all the rockers pitting. Ouch....

I had the cams refaced & reground by Tighe Engineering (great people) and bought 8 new rockers. I reassembled the bike (including cam-paste) and set everything to factory (full tune, new oil & filter) and went riding.

Rechecked the valve-lash about a month later at 35 000 k: all good. Rechecked the valve-lash at 40 000: pitting on cam lobes and rockers! Holy crap.

While I was having the cam and rockers refaced & reground by Tighe Engineering, I had a think: all these engines up to the ZX10 ran the head oil-supply line up the front of the engine which split (Y-shape) and went to two banjo oil fittings at the front of the engine. Internally, the oil went to the exhaust cam, exhaust rockers, two internal oil lines, inlet cam and inlet rockers in that order.

As the engine wears, the clearance of the cam in the cam-journals and the rockers on the rocker-shafts opens up and oil leaks out of these journals and shafts, compromising the oil flow to the inlet camshaft and the inlet rockers especially.

The fix is easy, cheap and simple: duplicate the oil flow configuration of the later (post ZX10) engines.

Remove the whole y-shaped oil line and use the rocker-shaft screws (right hand side of cylinder head) to blank the two oil line holes in the front of the cylinder head.
Fit a quality banjo fitting (hose type) to the oil pump outlet at the lower-front of the engine.
Go to the wreckers and get two long right-hand-side cylinder head oil fitting screws. I think the screws from the front of the cylinder head are long enough as well.
Fit a quality banjo fitting (hose type) to each of the new longer cylinder head screws on the right hand side of the cylinder head, facing each other and angled down so that they are at a 90 degree included angle. Check all depths and clearances carefully.
Fit some quality oil hose (about 4 or 5 inches to start with) and, trimming the hose so that it fits well, fit a tee-piece between them. I fitted the tee-piece so that one of the stems ended up facing down-forward.
Fit some quality oil hose from the pump outlet to the remaining vacant tee-piece arm. Avoid hot areas and make it secure.
Use the best clamps you can find and tighten.
With the cam-cover off & plugs removed, crank the engine until oil comes out of the rocker oil jets.
Important note: leave the internal oil lines intact! In this configuration, they serve to equalise oil flow across the head.
Set valve lash.
Assemble and run.

Now, having modified my Rx like this, essentially duplicating the oil flow pattern of the later engines, I had no camshaft, rocker or pitting trouble for the next 75 000 k, when I sold it and bought the Zrx. I wish I had a picture, but from the side with fairings on, (minor internal trimming required of the air path panels) you couldnt easily tell it had been modified. With the fairings off, it looked just like a big Y with the 'leg' of the Y running to the down-right at a 45 degree angle to the front of the engine. But it ran very well.

Hope all this helps, guys. Cheers,

Woof....... (Rex is four years old now with 98 000 on the clock and no more pitting. Sweet...

[bonester]

Interesting stuff Woof. I can't picture what you mean without the engine in front of me. I wonder how many engines pit cams due to oil supply probs?

[Gosling1]

thanks for that Woof ! great post mate, I will have a close look at doing this, because the motor is still apart and now would be the perfect opportunity to do this mod.....

The cam lobes and rocker arms in this motor are all in good nick at the moment, there is 48k on the clock, NFI if that is genuine or not, but I would tend to think that it might be, as the cylinder bores all look in great condition, and there is no evidence of a lip at the top of the barrel either........

[Woof]

Hi Bonester. Yeah, I know it's hard to describe. I should have taken a pic. Anyhow, take a look at the right-hand side of your engine.

In pre-1988 engines, the two large diameter Allen-screws just beneath the cam-cover secure the rocker-shafts. In post-1988 engines, the two Allen-screws fit the cylinder head oil manifold to the cylinder head as well as securing the rocker-shafts. Look at a ZRX1200 or ZZR1200 to see what I mean.

To modify the oil flow-path to eliminate cylinder-head oil-flow problems, a large part of the cam-pitting issue in the older engines, you need to duplicate the later oil-flow pattern.

I bought three banjo fittings, one tee-piece and some high-quality oil (6 or 8 mm internal diameter I think) hose from Pirtek in Toowoomba. Got a receipt somewhere.... I think the banjo fittings are 12 or 14 mm internal diameter and 6 or 8 mm hose-fit and the tee-piece is 6 or 8 mm hose-fit. (I just bought what would do the job and fit. I took the Allen-screws in to Pirtek in Toowoomba and asked for banjos to fit the screws, hose to fit the banjos and a tee-piece to fit the hose.)

Anyhow, after removing the original rigid Y-piece oil line from the engine (goes from the pump to the cylinder-head) and blocking off the now unused two oil holes in the front of the cylinder head, I fitted one banjo to the pump outlet at the lower-front of the engine. I pointed this oil-pump outlet banjo fitting in the general direction of the front-lower-right engine mount.

Back to the right-hand side of the engine. Bolt the two banjo fitting to the side of the engine using two large diameter Allen screws from an engine post 1988. These screws are about 10 or 12mm longer than the screws of engines pre-1988. Point the hose end of the front banjo fitting towards the oil filer cap. Point the hose end of the rear banjo fitting to the front engine mount. If you extend the line of the two banjo fitings, they make a 90 degree angle. Cool so far.

Take the tee-piece and using some short lengths of the high-quality oil hose, fit the tee-piece between the two banjo fittings. When fitted correctly, the tee-piece's remaining vacant hose-fitting end should be pointing towards the front engine mount. Now, get the oil hose and join the banjo fitting (on the lower-front of the engine) to the remaining vacant tee-piece hose fitting. Hose clamp everything well. Prime the cylinder head by cranking the engine either by hand (ignition cover off and use a socket and brace) or by cranking on the starter-motor. Oil flows to the cams and rockers right good! Note: in the pre-1988 engines, there are two internal oil lines that go between the two cams: leave them there!

OK: no photo makes it hard, but it is the best fix for pre-1988 engines once the cams and rockers have been repaired. I can recommend Tighe Engineering.

Cheers,

Woof.....

[s man]

Im a little lost here. If the engine is running low on oil pressure I doubt that would cause pitting.
In fact Im 99% sure it wouldnt. It would however cause scoring & bluing of the cam lobes .
"Pitting" is small pit/holes in the metal or hard facing of the cam.
Both two very different issues.

Pitting can be put down to poor metals being used, incorrect hard facing practices, or simply crap quality control at the manufacturing stage.
Not at all related to oil pressure/running in/cheap oil, which would all cause scoring/bluing of all working faces.
Just my 2 bobs worth.

[Neilp]

Im a little lost here. If the engine is running low on oil pressure I doubt that would cause pitting.
In fact Im 99% sure it wouldnt. It would however cause scoring & bluing of the cam lobes .
"Pitting" is small pit/holes in the metal or hard facing of the cam.
Both two very different issues.

Pitting can be put down to poor metals being used, incorrect hard facing practices, or simply crap quality control at the manufacturing stage.
Not at all related to oil pressure/running in/cheap oil, which would all cause scoring/bluing of all working faces.
Just my 2 bobs worth.

Finally someone here who understands something about metallurgy! This subject has been done to death on 2 well known US sites, and that was the eventual consensus there also.


Neil