Valve Clearance Queries

[Hack]

I've done this job many times on my Z900A4 and never really questioned the info in the shop manual before but having read the tutorial under "Members Technical" plus a whole host of other posts which have included this subject I have a couple of queries:-

When did the specified clearance change from 0.05 - 0.10 to 0.10 - 0.15?
I can't find the relevant service bulletin for this.
I have a genuine KHI 76 KZ900 shop manual and the clearances are still shown as 0.05 to 0.10 and it specifically says don't increase the clearance to a larger value as this "will cause valve lifter noise and retard valve timing".
Given that this manual is 4 years into Z1 production I would have thought that any valve seat burning issues would have come to light long before this and any necessary clearance changes would have been incorporated - they're not, clearance is still as original Z1.

The manual also has a conflict in specifying what position the camshaft should be in when taking the measurements:
The valve adjustment chart on pg. 182 shows to take measurements with the cam lobe pointing directly away from the valve (like most of us always have done) but the the instructions on pg. 156, the supplement for Engine No. Z1E18866->, which my A4 is, show to align marks on the sprocket rubber with the cylinder head surface and to then take readings from two valves at a time.
As no manufacturer ever implements a design change for no reason, does anyone know why this method change was specified?
Maybe to save time for the mechanic as doing it this way means you can check all 8 valves for four movements of the crankshaft - not much benefit to a home mechanic.
Maybe the cam profile is different, doesn't look that way to me.
Maybe it gives a more realistic value as would be found in the running condition (accounting for cam bearing wear).

What does bother me is that I get different readings by the two different methods - not a massive difference and the amount varies from valve to valve - just wish I knew why and which one to go by.

Some much more experienced Z brains than mine on here - what do you think?

Thanks,
Andy

[Philippe]

Hi Andy

I always take a clearance between 0,05 and 0,1 for the intake valves (closer to 0,1 or a bit more if possible) and between 0,1 and 0,15 for the exhaust valves( closer to 0,15 or a bit more if possible).
The exhaust valves get hotter , the intake valves stay cooler due to the passage of the fresch, colder mixture.
You also have to take the new fuel in account, a higher temperature and a higher octane ratio.
The Z1000 engines were supposed to run on fuel with an octane number of 92 which is no longer available in Europe. In normal fuel the octane number is 95 but with 10 % ethanol .
The 98 octane fuel has only 5% ethanol.
Ethanol is not good for the old rubber fuel lines and gaskets. If you already replaced those by new ones there should be no problem.
I always measure the clearance when the point of the lobe is pointing away from the shim and stands at about 180°in relation to the flat surface of the shim.
If you use clearances of 0,15 mm there will be no problem. Keep in mind that it's always better to hear the valves tick then no sound at all.
The cam profile is the same for the Z1 straight to the Z1000A4, only the number of sprocket teeth increased from 30 to 32 beginning with the Z1000A3 engine (square camshaft cover).
I hope this makes sense to you.
GrtZ
Philippe

[warren3200gt]

Hi Andy

I always take a clearance between 0,05 and 0,1 for the intake valves (closer to 0,1 or a bit more if possible) and between 0,1 and 0,15 for the exhaust valves( closer to 0,15 or a bit more if possible).
The exhaust valves get hotter , the intake valves stay cooler due to the passage of the fresch, colder mixture.
GrtZ
Philippe

Are you sure Phillipe?
Why is it that its the INTAKE valves are the ones that the gaps close up faster? Something to do with dia? ( intake being smaller)

[Philippe]

Hi Warren

I've never experienced that the intake valves close up faster.
Once the clearance is set correctly for all the valves, it stays good for a long time... perhaps because I almost never let the revs go higher than 5000 RPM and I always ride in a very cautious manner.
I've always been told that the intake valves stay cooler and that's the reason why they don't need as much clearance as the exhaust valves.
Correct me if I'm wrong please. I'm always prepared to learn more.
GrtZ
Philippe

[warren3200gt]

Hi Philippe,
I'm not sure where I got that info. You've got me questioning a long held belief now. It must have come from one of the myriad of manuals Ii have. Probably a 650 one as I've had them in my life for 40+ years.
You've peaked my curiosity now and need to verify.

[zed1015]

Clearances for both inlet and ex should be the same at 0.10mm to 0.15mm with them being set at the higher figure when servicing.
The inlet runs cooler due to the incoming charge and the exhaust hotter for obvious reasons.
The exhaust valve and seat tends to suffer more because of this and generally wears faster but not disproportionately.

[Gray17]

Afternoon guys, just reading this post with interest.
I recently had headwork done ( bikes not mine) which meant i had to set all of the valve timing and clearences afresh. Which i did however believe i set them slightly differently, however i remember reading that Kawasaki changed the clearence on later models.
So question what is the correct clearence on the Z900 A4 now and are both inlet and exhausts still the same?
Next i have recently had to restrip the head, barrells for a rebore, new pistons etc, after replacing everything back again i re checked the valve clearences. Which are way different to the settings i thought id set them too and what i wrote down after doung them the 1st time.
Now i know the clearences get smaller after a few miles on a re worked head but some of mine have got bigger after only 300 miles or so? So either i got them wrong to start with or ive misread them now. I do my valves with cam lobes fully upwards but is this correct as post says should be done facing forward?
My clearence are as follows:
Inlets 1 - 0.1mm
2 - 0.2mm
3 - 0.15mm
4 - 0.05mm
Exhaust 1 - 0.25mm
2 - 0.25mm
3 - 0.25mm
4 - 0.25mm
Whilst i know some are a bit loose, am i better letting it run for 1000 miles or so then re adjusting or do them now, bearing in mind i wont be reving it hard as new bores?
Thanks guys

[zed1015]

Set them at 0.15mm with the lobe pointing directly away from the shim (180 degs)..
With stock cams you are ok up to 0.17mm anything wider needs reshimming as does any below 0.12mm to bring them within 0.02mm of the 0.15mm ideal..

[sean_rfi]

I had my Z900 head set up by Dave at Buzzworkz because the seats needed recutting and the valves had to be tipped as well.
I checked the clearances after about 400 miles and they are all at 0.15mm or very slightly over this in line with what Rob has been saying.
The bike runs smoothly and pulls like a train (for a bog standard/stock set up, that is..)

[ADRIAN H]

Clearances should be set as Rob - zed1015 states, my Z1000A2 clearances were all set at 0.15 by DEBBEN performance and the bike purrs like a kitten.

[Gray17]

Thanks for the info guys, i assume both inlet and exhaust are the same and not different as indicated earlier in the post ie
The inlets less gap then exhaust due to cooling charge entry?
I did the checks this time with cam facing upwards ie 180 away from shim as Rob suggests, however a year ago i may well have measured the clearences with cam facing forwards. This is problem with me as a novice misreading posts. I will endevour to do it properly this time.
Thanks.

[zed1015]

Thanks for the info guys, i assume both inlet and exhaust are the same

Yes! Set both inlet and exhaust the same..

[DeadZedDave]

Hello Hack, your original post asked
"When did the specified clearance change from 0.05 - 0.10 to 0.10 - 0.15?"

Kawasaki, for the 1979 A3A model added a Supplement in the service Manual which states "specified valve clearance is changed".
SPECIFIED CLEARANCE ~ 0.05 to 0.15 mm for both inlet and exhaust.

As has been stated many times on this Forum. When actually SETTING and ADJUSTING clearances is a good idea to set to the maximum figure ~ 0.15 mm

The Service Manual specification is a simple service / check.

I ASSUME the 1979 Specification for A3A bikes is also applicable to A3 bikes also.

So that's 1979 Mk2 onwards = new specification.

As to the checking procedure, you also mention a conflict in the manual regarding where to set the engine / cam shafts for checking.
I personally do as zed1015 states.
Measure clearance with camshaft rotated 180 degrees from peak of cam lobe.
The alternative procedure offered in the manual whereby TWO valves can be checked at a time I believe is an expedient for workshop service mechanics to get the job done quick. The alternative set up still means the clearances are measured on the camshaft base circle.