Metallic knocking

[ROZZER]

Yet another issue has arisen, this bike is not coming around without a real fight!
On start up there is a pronounced metallic knocking sound from top end, this goes after approx 3-5 secs but can be heard intermittantly on tickover/just off tickover when warm but as I have said its not there all the time- Any Ideas???
New valves fitted - stems topped off 10 thou (12thou is max top off) to gain shim sizes as was down to 2.10mm on inlets, new guides, pistons, rings, camchain and damper rubbers 500 miles ago, cam shell bearings not replaced could they be the culprit? Valve clearances reset at rebuild all to 4 thou, I don't think they are the issue as the sound would be more of a ticking sound, am I right in that assumption?

[DogsbolloxofZ1B]

John,
Just resolved a very similar problem on a Z900, turned out the topped-off valve stems were not parallel to the shank and worse some were flush with the top of the collets... This may sound Ok but as the valve completes its upward movement against the shim bucket the protrusion on the inside of the bucket presses down on the collet rather than the valve stem and generates a 'metallic knocking' noise. I replaced the two defective valves with NOS & problem cured..

Another very satisfied customer...

[Garn 1]

Stab in the dark, could be your rotor has loosened. Need to pull off rotor and check three hex bolts, while you are at it check dowel pin. behind that plate, these break off giving a metasllic "tic-tic" but still work in a fashion.

Could be as Dogbollocks says. there is an amount of latitude that you can play with by grinding (about 1 mm) off the the top of the collet collets to give the stem tip some clearance. Never recommended, however, it can get you out of trouble.

Regardz.
PS. Did you re-tension your cam-chain?

[Rich]

If it oscilates (sometimes you hear it and sometimes you don't) have you had the valve stems ground? It may be the tips have not been ground square to the stem, especially if you and are having trouble with valve gap altering. If you put a screw driver to the head for every valve you will hear the bucket slap against the head when the cam picks it up. It oscilates due to the designed valve turn.

[ROZZER]

Thanks for the replies lads.
The noise is better described as a pinging knock, not a rattle or tick or deep wooden knock. As I descibed it can be heard on start up but goes very quickly as if oil getting up to top end eliminates it (or at least quietens to barely audible) reappearing periodically. This could tie in with rotating valve altering clearnce if not topped off square.
As I had the all the valve stems topped off at 10 thou (less than the 12 thou max quoted in manual) I thought that the collets hitting the bucket protrusion should not be an issue (the valve stems are still proud of the collets). Is it really likely that this is the cause of the sound. On further listening it definately sounds like its coming from the top end and seems to be from inlet side on No1 pot.
The bike runs fine all the way to the red line - I'm now worried, cos it sounds like there is a real danger of dropping a valve if the collet is touching the underside of the bucket.
The valve clearance is constant at 4 thou, not altering as if valve top was not ground square when topped off.

Camchain was retensioned

[Garn 1]

JohnR, when all else fails, do take a look at that rotor. I personally would have never thought of it! However a member of another forum came up with his diagnosis of a mechanical noise and was 100% correct worth a read.

Here is his explanation:

From: yoshipr (Original Message) Sent: 20/04/2007 11:20 PM
The engine rattle is coming from your stator magnet flywheel side there is a pin that shears off and causes the rattle and the ticking is caused by the plus and minus of slack and tension from crankshaft coming in and out of balance due to the sheared pin , so your cam chain is changing between tension and no tension very slightly, the same thing developed on my 73z1 #15883, continued riding can cause stress on all cam chain , parts and can result in cam chain tensioner failure.the pin is located between the magnet and fly wheel, I hope this helps you. Yoshi.

The above was an extract from:
http://groups.msn.com/WorldwideZ1Z900Ow ... 8861307881.

Worth a read, its a little disjointed (in three sections), however, could be what you are looking for! It slipped under the guard of many an expert. Further, I was replacing a rotor the other day when I noticed the hex bols were not very tight, I thought I would just have a look inside... Sure enough the pin was broken. This one had not sheared (like the above mentioned), but worn through!
RegardZ

[ROZZER]

Garn, Thanks for the advice, I have checked the rotor and it was fine, the key on the shaft was intact.
Noise is definately coming from top end I think from inlet cam side No1/2 cylinder area, it quietens just after starting which seems to indicate that oil pressure is having an effect. What sort of noise would worn cam bearings make? Years ago the old Ford Pinto engines in Capri's etc had cam wear problems that resulted in a really loud pronounced knock, mine is more metalliic and not really that loud.
I have tried putting my ear to a screwdriver around various points on the head but can't really pinpoint the noise- valve gear is very quiet (and should be considering all thats been done). Sound increases with revs but is never really loud just noticeable when you know its there, once above 2-3 k revs the general engine noise makes this knock inaudible.

[phil1r]

Hi, I know this is a old Post. But did you ever find out what the problem was. As I have the same noise from No2 inlet. Regards

[garyd]

Wasn't arouind when this was first asked but I've had quite a few that have done this and it was generally thought to be the cam moving sideways a little, especially on start up and sometime when just ticking over.

It's just one of those things that some do and some don't.

Not sure it it's the same as your problem though if you think it's coming from such a precise place.

[Coose]

My J does exactly this. It comes and goes, and is at its worse when the bike is warm and ticking over on the sidestand. Valve clearances are spot on and the cam caps are tight, plus it goes like stink so I'm in agreement with garyd - I suspect cam end float, which there doesn't look to be a great deal you can do about. I'll have a better look at the cam bearings at some point as I'm planning on eventually pulling the motor apart, but in the 800 (quite rapid) miles I've done on it the noise hasn't changed at all so I'm not going to lose sleep over it.

[johny brando]

Thanks for the replies lads.
The noise is better described as a pinging knock, not a rattle or tick or deep wooden knock. As I descibed it can be heard on start up but goes very quickly as if oil getting up to top end eliminates it (or at least quietens to barely audible) reappearing periodically. This could tie in with rotating valve altering clearnce if not topped off square.
As I had the all the valve stems topped off at 10 thou (less than the 12 thou max quoted in manual) I thought that the collets hitting the bucket protrusion should not be an issue (the valve stems are still proud of the collets). Is it really likely that this is the cause of the sound. On further listening it definately sounds like its coming from the top end and seems to be from inlet side on No1 pot.
The bike runs fine all the way to the red line - I'm now worried, cos it sounds like there is a real danger of dropping a valve if the collet is touching the underside of the bucket.
The valve clearance is constant at 4 thou, not altering as if valve top was not ground square when topped off.

Camchain was retensioned

I've had this noise or very similar before on past 900's ..... & to me ,it sounds more like a really bad knackered Big End !!!! If it is the same noise we are trying to describe, well most likely it's the Inlet Cam - now having excess thrust clearance........... To make sure that this is in fact the case & your not chasin your tail....well, this the only simple sure fired Acid test I came up with to positively identify the culprit .
This is best done when the engine is most likely to transmit the noise the most ( which is normally more prevelant when the motors cold ) .....so first cam box cover off & pop out the 1/2 moon rubber bung on the L/H side of the Inlet cam, & move the bike to an area where Oil spilage mess doesn't matter ( ...prehaps first put some Polythene sheet down under the bike ) as there will be some mess to clear up .....Ensure your oil level is well up first & then start her up, then try to encourage the noise ..... normally a low tickover will do to encourage this , or sometimes add to this by sitting on the bike leaning it & holding it there to one side... at say a 10 degrees list , then when it's making the knocking noise use a pre-formed small..... say 6 inch long x 20mm O/D piece of wooden dowel / broom handle end / end of a large screwdriver or similar ...something with a very slighty convexed face helps , carefully & gently, in a parrellel plain to the cam apply light pressure to the end of rotating Inlet camshaft ......the noise should instantly disappear if it is the Thrust clearance causing the problem. Yeh, yeh I can hear people saying ....How d,ya know it's NOT the exhaust Cam then ????? well......... it's because the Exhaust cam is constantly loaded to one side by the Rev- Counter drive...... so it's only ever the Inlet Cam!
Now you have to fix the problem, if it was indeed excessive Cam float & it's a gunna be fiddly what ever way you go ! ....... How ?
The last one I did about 15 years ago, well first I measured up & noted the total clearance that was present between Camshaft bearing face & corrosponing Cam Cap thrust face. " Always good to have reference points ...just in case ! " Then I had the Cam Cap Thrust face ( R/H side ) built up by a Tig weld then machined back to have a final running clearance of .005 - .010 Thou ( normally theres about ".020 Thou plus of float there " & I personally think that once the cap thrust face wears down to a certain point... the cam just then kicks off jyraiting from side to side against the 2 thrust faces ......but I do concede it is a quite rare issue )
I would in hynsight now prehaps try something a bit different...like have the R/H side Alloy Cam Cap bearing thrust face machined back.....so the then removed alloy could now accomodate say a 2.5mm thick Brass thrust bearing plate which you could easily fabricate then have it machined down to give the final required closed clearance we want ( you could maybe fix this plate into place on the cap itself by say nice closely fitting sprung steel roll pins in each end of the plate , these
running through the plate & into the Cap body itself with the head of pin fully driven home but sitting recessed back a little ...say .015 thou behind the machined Brass running face ) this may be better way instead of welding.... because to machine the welded inside thrust bearing face can be a bit fiddly & also there is a little inevatable Cap heat/welding distortion to deal with ( having said this welded Caps will / should /did ,still pull down OK, as due to the Caps shape, it doe's have some 'Get out of Jail '.......give in it ! )
Anyway ...food for thought & your call . It's only MHO for what it's worth.
Good luck & I hope you fix it OK . Johny B

[phil1r]

Thanks Johny, very good explanation. First time I noticed this noise, cold engine turning right around a traffic island. Engine warm and you cant hear it.

[Coose]

I wouldn't worry about it Phil - it's air cooled and will always be noisy compared to any modern water cooled motor.

[Gavin]

My old Z1100 shaft had a similar noise, I was told it was caused by "cam float"
And not to be to concerned