Need confirmation that timing is set wrong on my 1976 KZ900

Thanks for replies i have now taken taken the cam off again after bench shim the valves.I rotated the cam several times to se if it rotated more smooth and it did.The valves are in so it bumpy to rotate but it feels smoother now.I had a look at the new bearing shells and did not find any scratching, but it is only rotated by hand some times.There is one spot that may bee tight see pic.

Wookie58 wrote:

Does the earlier motor use the same bearings as the "J"

ALL Z1 through to  Z/GPZ1100 ( 903,1015, 998 and 1089cc ) aircooled fours use the SAME cam bearings and are interchangable.
These bearings come in only ONE size which is STD.
The different numbers and letters are only batch and date codes.
 

.I have now installed / replaced some new bearings on the exhaust cam also. After i installed the camshaft and checked the valveclearances i got surpriced ,because the
clearances now had big difference. 2 of the valves had zero clearance and one had big clearance .018mm.I checked the clearances before i installed the new bearings,  and they was all around .008  to .010mm with old bearings. I replaced the shims so the clearance is now in spec again,but started thinking that something is not right maybe the camshaft gets twisted from the pressure when clamping down and the bearings is not same as the old ??
I may try to install the old bearings and old shims again and remeasure...I will try to get some plastigauge again ,but have to order it from uk.

I don't think it is wise to set valve clearances "on the bench", without the head being torqued down onto the cylinder.
Just my observation...

H.

howardhb wrote:

I don't think it is wise to set valve clearances "on the bench", without the head being torqued down onto the cylinder.
Just my observation...

H.

It makes no difference to the valve clearance whether the head is on the bench or bolted down.
Once run the clearances will still need re -checking after the engine has been run and the valves have settled in , especially if the valves or seats have been re-cut.
Valve clearances should be set as close to 0.15mm as possible and after a valve job a little wider at 0.16 mm - 0.17mm is fine ..

zed1015 wrote:

howardhb wrote:

I don't think it is wise to set valve clearances "on the bench", without the head being torqued down onto the cylinder.
Just my observation...

H.

It makes no difference to the valve clearance whether the head is on the bench or bolted down.
Once run the clearances will still need re -checking after the engine has been run and the valves have settled in , especially if the valves or seats have been re-cut.
Valve clearances should be set as close to 0.15mm as possible and after a valve job a little wider at 0.16 mm - 0.17mm is fine ..

My opinion (and it is only my opinion) is that when the head is "loose" there can be an element of "distortion" (this is why there is a specific loosening and tightening sequence) I don't think the clearances would be effected but it may influence "how the cams sit in the bearings"
EDIT: This is in regards to Rolf's bearing concerns

Wookie58 wrote:

 

My opinion (and it is only my opinion) is that when the head is "loose" there can be an element of "distortion" (this is why there is a specific loosening and tightening sequence) I don't think the clearances would be effected but it may influence "how the cams sit in the bearings"
EDIT: This is in regards to Rolf's bearing concerns

Yes! In their free state some of these heads have a twist which can cause the cams to bind ( and affect cam journal clearance measurements ) when checked on the bench.
This twist straightens out once the head is re-fitted and torqued down.
Any heads that exhibit tight journal clearances or cam binding in their free state on the bench should be re-fitted and checked again before any attempt to rectify the issue.
Heads should also be checked for free state twist prior to skimming ( by checking that the cams spin free) otherwise once the head has been skimmed the twist will remain in the cam jounals when bolted down which will cause damage to the cams and bearing shells that mimics oil starvation.
 

Thanks for many advices. Well i now did a new check  by take out the new bearings and put in the old bearings again and bolted the camshaft on. The clearances was the same with old and new bearings so that was good!.  I think that the measurements i did back in september / oktober was not so acurate because then i did not bolt on the cam caps
i just held the cams down with hand when some valves was taken out .Anyway  the main reason i bench shim is that the valveseats was cut and then the valvestem can be to long so that there is not enough space for a shim and the valve has to be grinded shorter with a special grinder at a shop.
If not bench check i could run the  risk that after the head was bolted on the engine and camshafts and camchain refitted i vould have to dismantle  everything  again and send a valve to a shop for grinding the stem .Also if too long the valveseat have to be replaced.
And i almost forgot to say Never put both camshafts in at the same time when bench shimming that makes a great risk of bending valves !!

Rolf1976_KZ900 wrote:

i just held the cams down with hand when some valves was taken out .Anyway  the main reason i bench shim is that the valveseats was cut and then the valvestem can be to long so that there is not enough space for a shim and the valve has to be grinded shorter with a special grinder at a shop.

 

With the stock valves and collets you can tip the valves by 0.30mm to regain some clearance BUT if that isn't enough you can gain a further 1mm by skimming the collets and retainers and then tip the valves to suit.
All this can be done on a lathe.
 

zed1015 wrote:

 
 

With the stock valves and collets you can tip the valves by 0.30mm to regain some clearance BUT if that isn't enough you can gain a further 1mm by skimming the collets and retainers and then tip the valves to suit.
All this can be done on a lathe.

Okay thanks i did not know it was possible to skim the keepers..


 

I started to prepare the new camchain that i bought from z power uk.It is endless and i think it was included in the camchainrollersprocket and sliders kit if i remember right.I bought a masterlink because will have to split the chain.I use a cheap chainbreaker kit bought from ebay some years ago.

Here's a handy quick check tool from APE i'll bet would of saved you some time, they come in various sizes for different base circles. Stock is 1.110". This tool makes it easy to determine the finished stem end height to stay in the 2.00-3.00ish range. Final finishing required but gets you in the range at a glance. Like zed1015 said, if you've tipped the valve stems flush or below where the 2 collars fit then you HAVE to trim the tops of the collars otherwise you run the risk of that bucket protrusion kicking them out. And that isn't good, ha, but chances are you won't be laughing, just crying. I'm assuming you're using OEM valves? Seems other aftermarket valves are a bit longer than stock which require even more tipping.