z1 valve shims

[garybrez]

Hi .....

I recently got my cyclinder head back after some valve re-seating and replacement valves ... the valve tips were ground to help with shimming but i am having a mare with exhaust 2 & 4 ...

Popular to belief if the gap is too small add a smaller shim ( correct ?? )

I have no gap ( smallest feeler gauge 0.05 ) so I bought shims 2 sizes smaller than the shims that were fitted, just fitted em ( 2,50 ) and still no gap..

Before I order more shims how do I make sure to order the correct size to give me gaps of 0.10mm

Thanks

[Philippe]

Hi Gary

regrinding the valve seats is always a bit risky. You write that the valve tips are grinded off, so that means that there was allmost no play before the valve seats were regrinded.
I would suggest you start with the thinnest shim you have and see how much play you have and then order a correct shim.
I always start with a 2,00 mm shim and adjust afterwards, but then again I have a wide collection of shims so it's no problem for me ...
I hope that the valve seats are not regrinded too deep. When that happened I'm afraid you'll have to find another cylinderhead or have the valve seats replaced (if that is possible at all).
Good luck anyway!
GrtZ
Philippe

[zed1015]

If you have very little or no clearance with tipped valve stems and a .200 shim fitted you can skim up to 1mm off the retainers and a further 1mm off the stem tips to get you back in the high numbers for the shims.
After that you can fit bigger valves which use the unworn portion of the seats to regain normal clearance or even fit later J valves which have 1mm shorter stems to achieve the same result.
Plenty of options ( including fitting new seats ) before the head needs more serious work.

[garybrez]

OK so this is what I intend to do next ( Cylinder head bench set up )

I found a large penny washer 1.70mm thick, rotated cam lobe to vertical position then measured clearance of 0.40mm ( target clearance 0.10mm clearance is too big by 0.30mm )

by my calculation purchasing and adding a 0.20mm shim should give me clearance of 0.10mm

This is the same for both cyl 2 & 3 exhaust

Does this sound logical or is it a rant of a madman

[zed1015]

OK so this is what I intend to do next ( Cylinder head bench set up )

I found a large penny washer 1.70mm thick, rotated cam lobe to vertical position then measured clearance of 0.40mm ( target clearance 0.10mm clearance is too big by 0.30mm )

by my calculation purchasing and adding a 0.20mm shim should give me clearance of 0.10mm

Does this sound logical or is it a rant of a madman

Yes! Correct, but unless you can get 0.15mm with a thicker shim you will soon be under the limit with no way of adjustment.
Clearance is 0.10 to 0.15 and you should always aim for the higher number and re-shim once it reduces to 0.10mm.
Starting at 0.10mm and a 2mm shim leaves you nowhere to go and once the engine is started and the valves settle in a refurbed head your clearances will be under the limit within a few miles or maybe even before you get out of the drive.
You need to get the stem height reduced so you can get a mid to high range shim fitted around 255 and ideally 300 to give plenty of adjustment.

[rickm]

Don't want to thread-jack here, but in "normal" use after everything has settled in, how many miles do you normally get before having to re-shim to maintain clearance?
I know the recommended service interval is 3k miles, and I've got a couple of inlet valves that are already on a 2.00 shim

[zed1015]

Don't want to thread-jack here, but in "normal" use after everything has settled in, how many miles do you normally get before having to re-shim to maintain clearance ?
I know the recommended service interval is 3k miles, and I've got a coupe of inlet valves that are already on a 2.00 shim

How long is a piece of string ?
So many differing factors involved from one engine to the next.
I run my Z1R all year round and check them once a year regardless of mileage but generally i do more than 5k miles a year on that bike and haven't had a valve close up from max to minimum between checks.

[rickm]

Is that all on standard valves and springs etc?

[zed1015]

Is that all on standard valves and springs etc?

Race valve springs, 1mm o/s stainless valves.
Cams are stock, degreed in.
The bike doesn't get tootled around.

[garybrez]

Would 2.05mm or 2.10mm do it ?

[zed1015]

Would 2.05mm or 2.10mm do it ?

That's still cutting it fine .
While the heads off i would get the collets and retainers trimmed so you can get some decent size shims in.
It's money in the bank in the long run and you won't need the head back off in a few thousand miles.
What size shims are in the other valves ?

[garybrez]

2.60 ... 2.70 ...2.75...2.65 ... clearances between 0.08mm and 0.10mm.... I did not check if the new valves x 2 had been tipped, I am beginning to think not.

Anyway rant over .... I will buy 2.15mm shims which should give me top tolerance 0.15, prefer it to rattle a bit than all the clearances disappear on start up

Thanks for the help

[zed1015]

It won't rattle at 0.15.
That's the correct clearance and you should re-shim the other valves to match as those under 0.10 are tight,

[rickm]

Anyway rant over .... I will buy 2.15mm shims which should give me top tolerance 0.15, prefer it to rattle a bit than all the clearances disappear on start up

Thanks for the help

Unless I've misread, don't you need a 2.00mm shim to give you the correct clearance?
2.15 will leave you with nothing if a 1.70 had 0.4 clearance ?

[garybrez]

What to do .....

My original theory based on a 1.70mm shim giving me 0.40mm clearance, was to reduce the clearance by replacing the 1.70mm shim with a 2.0mm shim.

That should give me a reduction in clearance by 0.30mm ending up with 0.10mm clearance with a 2.0mm shim

I could go further by adding a 1.95mm shim instead of a 2.0mm. giving me 0.15mm clearance