84 gpz 750 cams in an 82 head and valve swap

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13 Aug 2022 21:06 #872194 by richard
I know this subject has been discussed many times
but there is no mention of shim difference when putting in the 84 cams with smaller base circle in an 82 gpz 750 head that accepts a larger base circle cam

The actual problem I'm having
Is my 84 gpz 750 head had some of it's seats sunk too deep , I then had to grind too much off the stem to stay within the shim selection,some of the exhaust valve stems were then too soft to use
my question is ,can 82 gpz valves be used in an 84 heads,the part #s are different,would like to hear from someone who has actually done it

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14 Aug 2022 15:49 #872234 by Nebr_Rex
Replied by Nebr_Rex on topic 84 gpz 750 cams in an 82 head and valve swap
Iirc the stems are longer, check the archives to confirm.
There is a lot of info there that is still relevant today.


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2002 ZRX1200R
81 GPz1100
79 KZ1000st daily ride
79 KZ1000mk2 prodject
78 KZ650sr
78 KZ650b
81 KZ750e
80 KZ750ltd
77 KZ400/440 cafe project
76 KZ400/440 Fuel Injected

www.dotheton.com/forum/index.php?topic=39120.0


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  • Scirocco
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14 Aug 2022 16:43 - 14 Aug 2022 16:44 #872239 by Scirocco
Replied by Scirocco on topic 84 gpz 750 cams in an 82 head and valve swap
The later GPZ (bath tub) heads have a steeper valve angle and need a different cam base circle.
Last edit: 14 Aug 2022 16:44 by Scirocco.

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  • TexasKZ
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14 Aug 2022 16:56 #872241 by TexasKZ
Replied by TexasKZ on topic 84 gpz 750 cams in an 82 head and valve swap

The later GPZ (bath tub) heads have a steeper valve angle and need a different cam base circle.
There was a 750 bathtub head?

1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough

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14 Aug 2022 17:20 #872243 by richard
Replied by richard on topic 84 gpz 750 cams in an 82 head and valve swap
I guess what I'm saying
if I put an 81 gpz 750 ex and intake valve into an 83 gpz750 head , would it work? And is it a mater of needing .5mm more shim thickness?

I'm trying to avoid removing too much material off the top of the 84 gpz 750 valve stems ,pic shows how soft they became after removing ,5mm from the valve stem, again was forced to do so after sinking the seat beyond spec
 

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16 Aug 2022 07:57 - 16 Aug 2022 10:31 #872336 by Daftrusty
Replied by Daftrusty on topic 84 gpz 750 cams in an 82 head and valve swap
*Edit*  So are you asking if the 82 valves are shorter than the 83-84 valves?? 
I misunderstood the question. So the issue is you need shorter valves because the valve pockets are cut too deep, thus putting  the valve stem height out of adjustment range.
If so, then no!  
You will need new valve seats installed and recut to the correct setup height. 

 Yes, the intake and exhaust valves from 1981-1993 kz/gpz/zr750 motors are interchangeable.
In 83, on the gpz, they recessed the exhaust valve seat to “increase flow” which then required them to make the exhaust cam a small base circle in order to accommodate the difference in valve stem setup height. (I guess it was easier to make a different exhaust cam rather than millions of special shorter exhaust valves) 
From what I noticed, any time Kawasaki used a different alloy, manufacturing process, vendor or part refinement, they would change the part number. Even if all the parts were functionally identical. Partzilla is a great resource as they update all the superseded part numbers that Kawasaki uses. So when they run out of a NOS part, they will offer the next compatible part # for that application. 

When I had my 81 head redone, I had them cut the exhaust valve seats deeper in order to accommodate the 84 gpz cams I was going to use. That put the valve shim closer to the middle of the range. I didn’t want to find that I couldn’t find a shim that would make up the .5 mil gap. 
 
Last edit: 16 Aug 2022 10:31 by Daftrusty. Reason: Misunderstanding

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16 Aug 2022 19:34 #872362 by richard
Replied by richard on topic 84 gpz 750 cams in an 82 head and valve swap
Thanks for the clarification
did realize after that all the valves  shared the same part number 
 

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