Shimming when there's no clearance
- chrispysaki
-
Topic Author
- Offline
- User
-
Registered
- Posts: 150
- Thanks: 0
Shimming when there's no clearance
20 May 2010 10:12 - 20 May 2010 10:12
Five of my valves have no clearance at all between the cam lobes and the other three are at about .7mm, which is a little under spec.
Is there a way to figure out what size shims I'm going to need? Maybe take the shim out altogether, measure the clearance and subtract the amount of clearance I need? Any other ideas?
Thanks!
Is there a way to figure out what size shims I'm going to need? Maybe take the shim out altogether, measure the clearance and subtract the amount of clearance I need? Any other ideas?
Thanks!
Last edit: 20 May 2010 10:12 by chrispysaki.
Please Log in or Create an account to join the conversation.
- timebomb33
-
- Offline
- User
-
Registered
- Posts: 4284
- Thanks: 10
Re: Shimming when there's no clearance
20 May 2010 10:23
do the buckets turn in the bores or are they too tight for that even
1973 z1 2-1974z1-a,2-1975z1-b dragbikes1015cc+1393cc, 1977kz1000,1978kz1000,1981kz1000j, 1997 zx-11, 2000 z12r,1428turbo nitrous pro-mod and a shit load of parts thats all for now leader sask.,CANADA
I THINK MY POWERBAND BROKE
I THINK MY POWERBAND BROKE
Please Log in or Create an account to join the conversation.
- BSKZ650
-
- Offline
- User
-
Registered
- Posts: 2061
- Thanks: 14
Re: Shimming when there's no clearance
20 May 2010 10:26
look at all your shims, and find the smallest, use it as a base line for the rest assuming you can get some clearance from the small shim
77 kz650, owned for over 25 years
77 ltd1000, current rider
76 kz900, just waiting
73 z1,, gonna restore this one
piglet, leggero harley davidson
SR, Ride captian, S.E.Texas Patriot Guard Riders.. AKA KawaBob
77 ltd1000, current rider
76 kz900, just waiting
73 z1,, gonna restore this one
piglet, leggero harley davidson
SR, Ride captian, S.E.Texas Patriot Guard Riders.. AKA KawaBob
Please Log in or Create an account to join the conversation.
- PLUMMEN
-
- Offline
- User
-
Registered
- Posts: 7986
- Thanks: 104
Re: Shimming when there's no clearance
20 May 2010 10:43
BSKZ650 wrote:
makes sense to melook at all your shims, and find the smallest, use it as a base line for the rest assuming you can get some clearance from the small shim

Still recovering,some days are better than others.
Please Log in or Create an account to join the conversation.
- Patton
-
- Offline
- KZr Legend
-
Registered
- Posts: 18568
- Thanks: 2101
Re: Shimming when there's no clearance
20 May 2010 11:07 - 20 May 2010 11:18
chrispysaki wrote:
If smallest feeler gauge won't fit between shim and cam base circle, but shim itself can be moved --- indicates existence of some minimal clearance. Could remove shim, determine its size, and replace with next thinner size.
If smallest feeler gauge won't fit between shim and cam base circle, but shim itself cannot be moved --- indicates no clearance whatever. Could remove shim, determine its size, and replace with shim two sizes thinner.
In any event, after measuring clearance, must know size of existing shim in order to determine needed replacement size.
With clearances properly adjusted to specs, it's a good idea to make note of each valve's shim size to keep with bike maintenance record. Then in future, will know replacement shim size needed from gap measurement alone.
Good Fortune!
Five of my valves have no clearance at all between the cam lobes and the other three are at about .7mm, which is a little under spec.
Is there a way to figure out what size shims I'm going to need? Maybe take the shim out altogether, measure the clearance and subtract the amount of clearance I need? Any other ideas?
Thanks!
If smallest feeler gauge won't fit between shim and cam base circle, but shim itself can be moved --- indicates existence of some minimal clearance. Could remove shim, determine its size, and replace with next thinner size.
If smallest feeler gauge won't fit between shim and cam base circle, but shim itself cannot be moved --- indicates no clearance whatever. Could remove shim, determine its size, and replace with shim two sizes thinner.
In any event, after measuring clearance, must know size of existing shim in order to determine needed replacement size.
With clearances properly adjusted to specs, it's a good idea to make note of each valve's shim size to keep with bike maintenance record. Then in future, will know replacement shim size needed from gap measurement alone.
Good Fortune!

1973 Z1
KZ900 LTD
KZ900 LTD
Last edit: 20 May 2010 11:18 by Patton.
Please Log in or Create an account to join the conversation.
- timebomb33
-
- Offline
- User
-
Registered
- Posts: 4284
- Thanks: 10
Re: Shimming when there's no clearance
20 May 2010 12:14
if the buckets will turn then i would go 3 sizes smaller on the exhaust and 2 sizes smaller on the intakes and that should get your right in spec or a little bit looser than spec. which is way better than tight.
1973 z1 2-1974z1-a,2-1975z1-b dragbikes1015cc+1393cc, 1977kz1000,1978kz1000,1981kz1000j, 1997 zx-11, 2000 z12r,1428turbo nitrous pro-mod and a shit load of parts thats all for now leader sask.,CANADA
I THINK MY POWERBAND BROKE
I THINK MY POWERBAND BROKE
Please Log in or Create an account to join the conversation.
- chrispysaki
-
Topic Author
- Offline
- User
-
Registered
- Posts: 150
- Thanks: 0
Re: Shimming when there's no clearance
20 May 2010 12:36
Thanks, all. I didn't check if the buckets will turn before removing the cams. I'll check that out and see if using the smallest shim creates any clearance and go from there.
Please Log in or Create an account to join the conversation.
- BSKZ650
-
- Offline
- User
-
Registered
- Posts: 2061
- Thanks: 14
Re: Shimming when there's no clearance
20 May 2010 13:07
what bike are you working on, since you removed the cams guessing its a under bucket shim
77 kz650, owned for over 25 years
77 ltd1000, current rider
76 kz900, just waiting
73 z1,, gonna restore this one
piglet, leggero harley davidson
SR, Ride captian, S.E.Texas Patriot Guard Riders.. AKA KawaBob
77 ltd1000, current rider
76 kz900, just waiting
73 z1,, gonna restore this one
piglet, leggero harley davidson
SR, Ride captian, S.E.Texas Patriot Guard Riders.. AKA KawaBob
Please Log in or Create an account to join the conversation.
- Patton
-
- Offline
- KZr Legend
-
Registered
- Posts: 18568
- Thanks: 2101
Re: Shimming when there's no clearance
20 May 2010 13:32 - 20 May 2010 13:33
Specified valve clearances for Z1~KZ900~KZ1000 with over-bucket shims are .05mm~.10mm, with shim sizes available in increments of .05mm.
Up to .15mm clearance is reportedly okay. But I would suspect loses some flow, however minimal.
Other KZ models, with under-bucket or over-bucket shims, have specified valve clearances which differ among the various models.
In this application, looser is better than tighter. "When they're click'n, they ain't stick'n."
Good Fortune!
Up to .15mm clearance is reportedly okay. But I would suspect loses some flow, however minimal.
Other KZ models, with under-bucket or over-bucket shims, have specified valve clearances which differ among the various models.
In this application, looser is better than tighter. "When they're click'n, they ain't stick'n."
Good Fortune!

1973 Z1
KZ900 LTD
KZ900 LTD
Last edit: 20 May 2010 13:33 by Patton.
Please Log in or Create an account to join the conversation.
- chrispysaki
-
Topic Author
- Offline
- User
-
Registered
- Posts: 150
- Thanks: 0
Re: Shimming when there's no clearance
20 May 2010 14:21
It's an '80 kz750-4. Underbucket shims. Spec clearances are .08 to .18.
In my original post I reported .7mm, but that should have been .07.
In my original post I reported .7mm, but that should have been .07.
Please Log in or Create an account to join the conversation.
- timebomb33
-
- Offline
- User
-
Registered
- Posts: 4284
- Thanks: 10
Re: Shimming when there's no clearance
20 May 2010 17:28
that is why i use standard measurements instead of metric. no confusion that way. i try for .004"=.10mm intake .006" =.15mm exhaust. besides my feeler gauges read in standard.
1973 z1 2-1974z1-a,2-1975z1-b dragbikes1015cc+1393cc, 1977kz1000,1978kz1000,1981kz1000j, 1997 zx-11, 2000 z12r,1428turbo nitrous pro-mod and a shit load of parts thats all for now leader sask.,CANADA
I THINK MY POWERBAND BROKE
I THINK MY POWERBAND BROKE
Please Log in or Create an account to join the conversation.
- Jonny
-
- Offline
- User
-
Registered
- woot!
- Posts: 210
- Thanks: 22
Re: Shimming when there's no clearance
04 Jul 2010 10:49
I hope this isn't highjacking, but I'm doing some of the same work, on my 78' 650 and just waiting for a day to pull the cams and find out just what size shims I have in there.
I'm getting some chatter, and none are over 0.010", so all very close to spec clearance. However, a few get no clearance on my smallest feeler gauge, which is 0.08" (spec). So while its hard to say what the actual clearance is, none of the buckets are completely immobile.
Reading through this string, I wonder if anyone has any tried and true advice on adjusting the clearances in this model/engine? I figure I'll just shoot for manual specs. But I gather generally a little looser, especially on the exhaust side is gonna be a.o.k? I understand the principles at work here, and am not attempting to sqeeze every ounce of possible performance out of the engine, rather have it run reliably and last a good long time. (which it does currently, and should continue to do
Thanks,
Jon
I'm getting some chatter, and none are over 0.010", so all very close to spec clearance. However, a few get no clearance on my smallest feeler gauge, which is 0.08" (spec). So while its hard to say what the actual clearance is, none of the buckets are completely immobile.
Reading through this string, I wonder if anyone has any tried and true advice on adjusting the clearances in this model/engine? I figure I'll just shoot for manual specs. But I gather generally a little looser, especially on the exhaust side is gonna be a.o.k? I understand the principles at work here, and am not attempting to sqeeze every ounce of possible performance out of the engine, rather have it run reliably and last a good long time. (which it does currently, and should continue to do

Thanks,
Jon
'78 KZ 650C2 'Lila'
'71 Norton Commando 750 'Eadie'
St. Catharines, ON (Mostly, anyway...)
'71 Norton Commando 750 'Eadie'
St. Catharines, ON (Mostly, anyway...)
Please Log in or Create an account to join the conversation.
Moderators: Street Fighter LTD