Need confirmation that timing is set wrong on my 1976 KZ900

Okay i was planning to anneal the 4 old copper washers i did not know that i needed to anneal the new ones also

Keep going Rolf.  I'm really getting a lot of information from your descriptions and the responses.

Rolf1976_KZ900 wrote:

Thanks asphalt900  for the tip. I use the valves that was in the engine not sure they are oem but i think so. I did not have to grind any of the valvestem ends to fit shims into the 2 valves that had zero clearance .The smallest shim that is installed now after adjustments is 220 so that is good.

I don't know how i missed this but if you are in the low 200's on those shims you really need to tip the affected valves.
You will soon run out of clearance very quickly with 220's once the engine is run and the valves settle in and will be in a situation where the head needs to be off again.
Ideally you need to get the shims in the 255 and above range to give enough scope for settlement and still have enough shims sizes for future adjustment..

Agreed I had to do it on my other head. 

.I have now been thinking alot and unsure if i need to tip the valvestem on one valve.   .I think it is in the safe zone not to tip . The valve that has the smallest shim installed  2.20mm has now a clearance  at 0.12mm.  That gives  4 smaller shimsizes to go on plus the clearance is already  now 0,12mm .
I have cut valvseats a couple of times before and from the notes i did on the latest head after first  bench shimming and then checked clearances after engine was run first for 100 kilometers then rechecked the valves some times up to some thousands kilometers  i found that the amount valves settle/sink into the seat is not much.(That has been on yamaha heads) The adjustments needed on the valves after some running was very small  it was like going from 250mm to 248mm half shim sizes ,but one the last head i did one of the valves  had a bigger drop i shimsize.Not sure why that valve had a big drop in clearance, but it  may be i typed wrong size on that valve when bench shimmed.I have note after engine has run about 28 000km but can not find it now but the clearances has stayed stable

  I have found some notes i did on the latest yamaha head .That has been 16 valve heads and the valvespring force is less .This 8 valve kawa has stronger valve springforce that may contribute to more force pressing/hammering the valve into seat ,but the main pressure is from the combustion i think.. Anyway the main reason i may not tip the valve is that  i think the valves are  oem (they are magnetic) and they may have a hardened thin surface coating at the end of the valvestem .I read if that type of valve is tipped it will vear down the valvestem end  fast.?

If the valves was stainless  aftermarket  i read that  it is no problem grinding down the end of valvestem . So not sure if i will replace that valve with a stainless steel valve or just trust the data i have from other valvejobs  that it will not have a big drop in clearance when valve beed in.If i have to get a new aftermarket stainless valve i will have to get a shop  grind it down.

Forget the 16v Yamaha head.
The valves are very much smaller and lighter and don't impact the seat compared to the larger 8 valve KZ which can settle significantly depending on the seat cut.
I have done hundreds of these heads and you really need to rectify that valve now to save you more work in the very near future unless it's barely going to get used or you are selling it on..
The stock valve is safe to tip more than the 0.3mm but the collet and retainers need trimming too.
Also that 0.12mm clearance will close up once the valves bed in and you will be close to or below the minimum 0.10mm clearance so you need to aim for upper 0.15mm figure or slightly above around 0.17mm to allow for settlement which means that you really need a 215 shim to be fitted as it is now so you actually only have 3 shim sizes left which can drop to 2 once the bike has been run..

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zed1015 wrote:

Forget the 16v Yamaha head.
The valves are very much smaller and lighter and don't impact the seat compared to the larger 8 valve KZ which can settle significantly depending on the seat cut.
I have done hundreds of these heads and you really need to rectify that valve now to save you more work in the very near future unless it's barely going to get used or you are selling it on..
The stock valve is safe to tip more than the 0.3mm but the collet and retainers need trimming too.
Also that 0.12mm clearance will close up once the valves bed in and you will be close to or below the minimum 0.10mm clearance so you need to aim for upper 0.15mm figure or slightly above around 0.17mm to allow for settlement which means that you really need a 215 shim to be fitted as it is now so you actually only have 3 shim sizes left which can drop to 2 once the bike has been run..


Okay Zed1015  not going to argue .I will then try to find  a shop that can grind 2 valves ex 3 and 4 . If they are grinded 0.20mm do the collets need any work?     I will aim for 015-0.17mm
Here is what i got now also have to buy a few more shims.

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As long as the valves haven't been tipped before you can remove 0.30mm before touching the collets so i would remove the maximum 0.30mm which should at least get you to the 250/255 shim range.
As an indicator the distance from the top of the collet groove to valve tip should be a minimum of 4.2mm after tipping.
If they are already 4.2mm they may have been tipped already.
On all those other valves you should re-shim as close as possible to the upper 0.15mm clearance.
If the next shim size takes the clearance to slightly above to around 0.17mm this is ok .

I have not taken the valves out yet but did a quick check with a 0.30mm felerblade that is pressed down on the keepers.so it is not tipped before i think.

zed1015 wrote:

...
On all those other valves you should re-shim as close as possible to the upper 0.15mm clearance.
If the next shim size takes the clearance to slightly above to around 0.17mm this is ok .

Just wanted to ask why the earlier 1000's and the '76 900 have a clearance range of 0.05-0.10mm in the service manual and then they changed it to 0.05-0.15mm for the later bikes. Was there a reason for the change or did they just think the earlier range was too tight? 

calum wrote:

zed1015 wrote:

...
On all those other valves you should re-shim as close as possible to the upper 0.15mm clearance.
If the next shim size takes the clearance to slightly above to around 0.17mm this is ok .

Just wanted to ask why the earlier 1000's and the '76 900 have a clearance range of 0.05-0.10mm in the service manual and then they changed it to 0.05-0.15mm for the later bikes. Was there a reason for the change or did they just think the earlier range was too tight? 

The clearance was widened due to instances of valve burning, Especially the exhaust.
It is actually 0.10mm to 0.15mm not 0.05mm to 0.15mm.
There are many manuals that have increased the upper limit but incorrectly retained the lower which was also increased which is pointless as it is the lower limit that was the cause of the problem..
 

Zed, do you know if Kawasaki issued a service alert on valve clearances?