TOPIC:

For the KZ750, a common modification is to change out the GPZ cams for a higher lift and longer duration to change the powerband on a KZ750. I found what may be a good deal on a set on Fleabay however I want to make sure I’m buying GPZ cams and not a set of standard KZ cams especially when there’s nothing wrong with mine. I’ll add the eBay item number and hopefully someone more versed in the KZ750 internals can tell.
eBay:
295815656968

Not sure about the 750 but the manual for the 1000/1100 has details of the identifiers for all the different versions

Here is what the fsm has to say, which ain’t much.

 

The cams in question are claimed to be from a 1982 GPz750.  As I understand it, those cams have the same lift and duration as the regular 750 cams, only they don't have a tach drive.

The fsm says the GPZ makes a few more horsepower than the other versions. If the cams are the same, I wonder where the other ponies came from. Could the BS34s really make more power then the Keihins?

GPZ/ZX 750/1100 cams have more lift and duration.

 
 
 
 

TexasKZ wrote:

The fsm says the GPZ makes a few more horsepower than the other versions. If the cams are the same, I wonder where the other ponies came from. Could the BS34s really make more power then the Keihins?

GPz has more compression, better flowing carbs, and the bath tub head.  And I'm not sure, but I think the exhaust flows better.

 

Nessism wrote:

The cams in question are claimed to be from a 1982 GPz750.  As I understand it, those cams have the same lift and duration as the regular 750 cams, only they don't have a tach drive.

Bingo!!!! We have a winner.
The Uni Tracks got the bigger cams except for the '82 GPz1100, which had 8 degrees more duration than the '81 model that has standard 'J' cams.
I do not know what the difference in lift is.

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I do believe the bathtub head has a little small chamber.


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Something I found from another thread. When they say "real GPZ cams"  they mean '83-'85 because as mentioned in '82 they were the same as KZ750 performance-wise; from what I've read '82 GPZ lobes were wider (not taller) and no tach gear on exhaust cam:

"The easiest way to identify the real GPZ cams is to just measure the lobe height.
Just use a vernier caliper to measure the complete lobe on the cam.
If it is 36,15 mm (1,424 inch) high, you have the wrong (standard) cams...
Inlet should be 36,65 mm (1,444 inch)
Outlet should be 35,65 mm (1,405 inch)
They were only installed on the GPZ750A1 - A3."

I've asked a seller to measure the lobes when I wasn't sure what year they were. I will also mention the good GPZ750 cams are getting hard to find, lots of KZ750 and '82 GPZ out there but not '83-'85 GPZ.

Indeed. If you take a look at the 1983-85 supplement in the back of the fsm, the specs clearly show a change in 1983, compared to the numbers posted by Nessism above. See pages 343 and 358, for example. 

www.kzrider.com/modules/ServiceManuals/GPz750.pdf

So what I gather here is that in order for the cams to be any different than the ones I have, they need to be from a 83-85 GPZ A1-A3. and the only way to tell is have the lobe heights measured and compare them to the specs given by Franklin. The seller claims they come from a 82 but that’s based on the engine serial number since he got the engine only and matched the GPZ title back based solely on the serial number. Likely not the cams I’m looking for unfortunately.