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Valve shim sizes on the limit! What next?

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rickm
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Valve shim sizes on the limit! What next?

#1 PostAuthor: rickm » Fri Mar 15, 2019 10:43 am

Just thinking ahead a bit here.

I bought my J from what I believe was a respected Z specialist.
It came with a refurbished head, so I thought I’d check the valve clearances after a few hundred miles to allow for bed-in etc. Most clearances were tight and needed re-shimming. My concern now is that all of the shims are on the lower (thin) end of the scale (two are 2.00, one at 2.05 and one at 2.10) so there’s no margin left before some headwork might be needed.

I’ll check clearance as per recommended intervals. I had a J back in the day, but can’t recall how often shims actually needed changing in a healthy “run-in” engine. So, how many miles am I likely to have left?

What are my options for when I can’t get the correct clearances anymore?
May just go the full whack with bigger valves and flowed head?

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Re: Valve shim sizes on the limit! What next?

#2 PostAuthor: zed1015 » Fri Mar 15, 2019 11:21 am

Most common cure with the current seats is to fit bigger valves which will sit further out on the unworn part of the seat and regain the clearances.
This is the main reason that most heads got bigger valves rather than for performance reasons.
You can also try new stock valves to see if that does the trick or another option is to use reduced base circle cams.
If you have access to a lathe you can also take up to 1mm off the collets, retainers and valve tips to get you back in the high shim range.
Ignore anyone who says you can't tip the valve that far as it will break through the hardening and wear prematurely.
The tips are sat under the bucket and not getting hammered by a rocker arm so this doesn't happen to any significant extent.
My Z1R has been running like that since i built it 20 years ago and has covered at least a hundred thousand miles with no issues and very few shim swaps from one year to the next.

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Re: Valve shim sizes on the limit! What next?

#3 PostAuthor: rickm » Fri Mar 15, 2019 11:35 am

Thanks zed1015 great info.
Presume there's no chance of running a thinner shim than 2.00 ?
I guess at some point the cam lobe would start to clip the edge of the bucket ?
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Re: Valve shim sizes on the limit! What next?

#4 PostAuthor: Ultim8pc » Fri Mar 15, 2019 12:19 pm

If you've run out of clearance (i.e smallest shim is too big) then you can remove the valves and have some material ground off the ends.
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Re: Valve shim sizes on the limit! What next?

#5 PostAuthor: zed1015 » Fri Mar 15, 2019 1:06 pm

rickm wrote:Thanks zed1015 great info.
Presume there's no chance of running a thinner shim than 2.00 ?
I guess at some point the cam lobe would start to clip the edge of the bucket ?

I had a couple of 1.9mm shims in with a load i bought a few years back but haven't seen any new for sale.
Think they were probably out of something else or aftermarket.
There's a few other bikes that use 29mm shims, some BMW etc so maybe they go down that thin but there's a limit before they might distort or shatter.
Personally i never fit a 2mm to mine unless it's an emergency and just pull the heads to sort it.

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Re: Valve shim sizes on the limit! What next?

#6 PostAuthor: ZedHead » Sat Mar 16, 2019 10:31 am

Ultim8pc wrote:If you've run out of clearance (i.e smallest shim is too big) then you can remove the valves and have some material ground off the ends.


As he said.

If you are keeping current seats, tip the valve stems as per the manual

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Re: Valve shim sizes on the limit! What next?

#7 PostAuthor: rickm » Sat Mar 16, 2019 10:38 am

Is that what it states in the factory manual? (I've not got one)
Some folk seem to suggest this isn't such a good idea, but if Kawasaki say it's ok !
Maybe better to take just 0.5mm off the tip rather than the full 1.0 ?
Last edited by rickm on Sat Mar 16, 2019 12:49 pm, edited 1 time in total.
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Re: Valve shim sizes on the limit! What next?

#8 PostAuthor: ZedHead » Sat Mar 16, 2019 11:13 am

You can download a manual from here.

https://www.dropbox.com/s/gwhhsj0qgwzi9 ... Manual.pdf

Section 3.8 informs you that you can grind off up to 0.3mm leaving a minimum of 4.2mm to the groove.

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Re: Valve shim sizes on the limit! What next?

#9 PostAuthor: zed1015 » Sat Mar 16, 2019 11:19 am

With stock unmodified collets and retainers Kawasaki recommend tipping the stems 0.3mm max.
This will get you around the 230 shim range.
Obviously Kawasaki err on the safe side to leave plenty of clearance so there's no risk of the bucket riding on the collets.
In reality you can squeeze a bit more depending on the amount of stem protruding above the collets and another 0.1mm gets you up to 140 shims.
On stock valves there is some slight variation from year to year due to manufacturing tolerances etc .
You will need to check that yours have not already been tipped and if not go take 0.3mm.
If you want a bit more then you could use a combination of methods.
Main thing is to know what you are doing.

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Re: Valve shim sizes on the limit! What next?

#10 PostAuthor: Pigford » Sat Mar 16, 2019 11:38 am

I had a #180 shim which was handy for checking tolerance of a head with tight valves - loaned it out a while back and never seen it again :??
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Re: Valve shim sizes on the limit! What next?

#11 PostAuthor: rickm » Sat Mar 16, 2019 12:57 pm

Thanks guys, all really good info :up
Having just changed the shims, hopefully I've got a few miles yet before any remedial action's needed.
I don't have access to a lathe, so would need a shop to do it.
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Re: Valve shim sizes on the limit! What next?

#12 PostAuthor: kev edwards » Sat Mar 16, 2019 10:31 pm

The head on mine was re-furbed by buzzard and has stainless valves the collets and retainers have also been machined down to allow for thicker shims
Last edited by kev edwards on Sun Mar 17, 2019 9:07 am, edited 3 times in total.


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