Visual difference between GPZ & KZ cams

Elfarm98648 wrote:

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.

Correct, as the seller is breaking the complete engine can you ask him for the full engine number. You should then be able to identify what he is selling. Don't forget that the 83 model year would have been produced from June/July 1982 so if he is basing it as an 82 based on registration date it could be an 83 model year motor 

 

There's a NOS ZX750 inlet camshaft (12044-1067) listed on EB out of Bulgaria. Item # 275768813679.
I have no idea if the part is actually what it's purported to be. If it is, then the pics might be useful.

12044-1067 275768813679

One other thing, the listing in the original post shows the part numbers and assuming they are accurate would be for '82 cams. The one shown from Bulgaria is the right part number for a later intake cam but it's expensive.

Still, may be worth the time to ask the seller to measure the lobes. I've done that twice on eBay and got answers both times. One set was the '82s but another set that was listed for KZ750 actually measured out as the later GPZ cams.

Franklin wrote:

One other thing, the listing in the original post shows the part numbers and assuming they are accurate would be for '82 cams. The one shown from Bulgaria is the right part number for a later intake cam but it's expensive.

Still, may be worth the time to ask the seller to measure the lobes. I've done that twice on eBay and got answers both times. One set was the '82s but another set that was listed for KZ750 actually measured out as the later GPZ cams.

I guess this is the lottery buying parts from 40 year old bikes, unless the seller is the original owner who knows what has been swopped around in it's past 

If the seller is willing to share the engine number, you can check it against the list here to see what year it is.

www.kzrider.com/filebase?task=download.s...id=1178&catid=64&m=0

Not sure any of this will be of any help or not. Here are some things I have found in the past regarding 650/750 cams,values and head info.  Take all of this with a grain of salt as I am not claiming the data is true, rather I found it somewhere on line in the past.

valve size  same till F2
intake 33 mm or 1.299 inches
exhaust 28 mm or 1.102 inches

F2 
intake 34
exhaust 30

the 750s are the same as the F2 

all models other than F2 are the same -
intake open 22 BTDC
intake close 52 ABDC
intake duration 254
exhaust open 60 BBDC
exhaust close 20 ATDC
exhaust duration 260

F2 differences 
exhaust close 22 ATDC
exhaust duration 262
F3 goes back to other settings?

bore and stroke
62 X 54 mm or 2.441 x 2.126 inches 

head volume #s are 
77-80 23.7
81 23.3 to 24.1 or average of 23.7  same as early one
82 24.8



Interesting Facts, Re Head swapping z750 heads/cams/stuff

Valves are bigger in the 750 head.
z650 head 32/27 (in/ex)
z750 head 33/29
As are the intake runners, but I don't have the 650 head to measure currently, but definately by a couple mm (3-4 off hand, I measured once)

Combustion chamber volume is similar enough to be irrelevent. (esp if machined)
650       23.3-24.1cc
750H     24.8 +-0.4cc
750L     25.3
Gpz750  25.9
Turbo    24.6

Cam heights. (in mm)

z650     35.73-35.87 (both)
z750     36.245-36.353 (both) So 0.5 more lift!
gpz750  36.746-36.854 (in) (So 0.5mm more again)
           35.746-35.854 (ex) similar to 650, but longer duration. 286 vs 260 (Or 262 on the F models)

Turbos have 650 cams.

Also BEWARE, SOME camshafts/head have a different base circle diameter most are 1.100" some are 1.070, rare ones are 0.900!

z650s have a differnet 5th gear ratio than 750s. 24/27 (750 21/24) Discovered this one long ago. Turbos are completely different.

early z750s (E/H) ran Keihin CV34 carbs..  later ones and Gpz ran Mikunis BS34. I had a set of Keihins for years- Excellent carbs (Have 2 sets spare)
One reason is the Keihins run a Primary and Secondary Main Jets. Mikunis have One.

KZ700s ran a 64mm piston. (66 for 750, 62 for 650) Sounds like a suitable alternative to a Wiseco kit. Same size...

Turbos have a 16mm Gudgen pin (wrist pin), instead of 15mm. And flat top pistons.

Early GT750s have a little hole in the conrod, that squirts oil under the pistons, and onto the cylinder wall.

Thats enough for now.

Sean

So I got some cams today that were supposed to be GPZ750. But they have a ring on one end. Here's a photo next to the Andrews cam I got from Nebr_Rex.

Can I assume these are not Kawi 750 cams at all because of that ring there?

Those cams with the flange on the end won't fit into a 750 head.

P1010284 by nessism , on Flickr