Andrew Cams Question...

I posted text from this but since I found a photo of the catalog page thought I'd add it:

I did a cleanup on a junk head I bought for $20 a few years ago. I smoothed out the casting marks and slag left behind from the casting process and improved the transitions at the cast in seats and at the intake manifolds. There were minor shelves at those points so smoothing them out made a big improvement. I remembered an article years ago saying KHI did a good job with their intake streams and to be careful about changing them if porting was to be done. The exhaust I left alone for the most part just a light cleanup. Originally I started with a 1015 Wiseco big bore kit and stock cams. Good power gain. Then Andrews 1X cams, a little better and rode the piss out of it.   Later I installed Mikuni VM33's and noticed even more power. Later I had to buy a 1015 block, the new style Wiseco kit and a complete overhaul including going back to the 903 crank. EVEN MORE POWER.   My stock head was getting tired and larger valves were in order so I turned to the junk head I'd been playing with. I took my time and when it was ready I installed it.   MAN that engine came alive.   It wasn't my plan to do these things one at a time but $$ was the deciding factor.   Early this year I sent my new 1075 kit and spare 1015 block to APE then installed it. IT RUNS LIKE A DIFFERENT BIKE.   
Looking back on all of this it would have been better to do it all at the same time but I wouldn't have known what each stage bought me and I was able to ride in the process.  Besides the big bores I think the porting had the best change for little or no money.   In time I will go back to my old head, install larger valves, hotter cams and do the same porting I did with the junk head I saved from the scrap heap. 
Like they say "It's not a job, IT'S AN ADVENTURE." 
Steve

For those more familiar with 750 heads than I am, does this look like a 1982 GPZ750 head that was factory massaged? (This is the best shot available looking down the ports.) I have engine serial number (KZ750EE073018) if that would help narrow it down.

I was under the impression that the factory didn't "port" the GPz heads per se, it was more a matter of removing machining and casting flaws?  

On my 750, where were some sharp edges around the valve pockets, and the valve seats were cut poorly; the seat width varied quite a bit from one side to the other

I cut the seats using Neeway cutters, truing them up, and massaged the sharp edges, blending them into the port.  I did NOT increase the port sizes, just blended, particularly on the short side radius, which had a nasty sharp-edged shelf.  

 

The article I was talking about was for the big fours. It seems KHI got lazy with the later ones. All kinds of trash and mismatched seats. My Z1 head is better. 
Steve

Franklin wrote:

For those more familiar with 750 heads than I am, does this look like a 1982 GPZ750 head that was factory massaged? (This is the best shot available looking down the ports.) I have engine serial number (KZ750EE073018) if that would help narrow it down.

 

Easiest way to tell if a black head is GPZ is the valve size, they have bigger valves than the KZ 750. The GPZ hand porting thing is a myth, they did not do any "hand work" on them but they did have more post cast machining than the regular KZ head. The combustion chambers are also bigger than a KZ head.

Injected wrote:

 

Easiest way to tell if a black head is GPZ is the valve size, they have bigger valves than the KZ 750. The GPZ hand porting thing is a myth, they did not do any "hand work" on them but they did have more post cast machining than the regular KZ head. The combustion chambers are also bigger than a KZ head.

Actually, the GPz750 uses the same valve PN's as the standard 750's.

There is one 750 head variant that uses a bathtub combustion chamber.  One of those heads may work well, as long as your piston kit plays nice with them.  They are reputed to be the best flowing of all the 750 heads.  Last photo shows standard 750 head...

 



 

Yeah, I just checked that, must have been thinking 650 vs 750.

This is from my notes:

The Kz750 H 24.8cc and Kz750 L 25.3 cc. The 82 GPz750 has a combustion chamber volume of 24.9 cc. The 83-85 GPz750 have chamber volumes of 25.9 cc (bathtub)

Not sure on the port sizing. I have a spare 82 Spectre head which is the same casting as GPZ I could check if needed.

Franklin wrote:

I've been studying cams to go with the 810 big bore kit for a 750E. I know the GPZ cams are a good option but came across some old Andrews cams, both intake and exhaust. Hard to find info on them, they are number 15. Only specs I found are from an old post on this site:

"Andrews offered the following grinds for the 650/750 Kawasaki
10 - 236 .330 - Bolt in Stock cups & springs 2500RPM+
15 - 244 .340 - Same as above but for 750cc
20 - 252 .350 - Modified engines up to 82 3000RPM+ stock springs and cups
25 - 260 .360 - 82 & Later Stock springs OK piston clearance needs checking more power from 3000RPM
30 - 270 .370 Best cam for big cc street motor. Springs, cups and collars sould be upgraded. Power comes on from 3000RPM+
35 - 274 .380 - Street/drags 800cc and up. Fully modified engines rurn on from 5000RPM up. Springs, cups, collars should be upgraded
40 - 262 .392 - Drags and big motors. Springs and cups required. Broad torque to 11000RPM"

The #15 there looks like a grind in between stock and the GPZ cam. Would that work well with the 810 big bore kit? Or would I be better off looking for a GPZ cam? (The Andrews exhaust cam has the tach gear so that's a positive.)

I have a set of both NOS No. 10 and No. 15 cams in somewhere in my stash, if interested I can dig them out.


.
 

Thanks for all the responses, I got busy with other stuff and didn't check back here for a few days. Definitely learning here!

So there's a head for sale described as from an '82. But it is the bathtub type so I'm thinking it must be from a later one. Do I have it right that later ('83-'85) flow the best? I had been thinking the '82 is the best because it has smaller combustion chamber and is cleaned up from factory.

Also, that head comes with cams so if not an '82 will have the hotter cams included. Then I wouldn't need the Andrews cams.

Still looking into an '82 GPZ head that's for sale. I was wrong about how the combustion chamber looks. Seems the '82 will look very similar to the '83+. Here's a shot from a Cycle World article back in '82. I'm still wondering how the later '83+ heads flow better than the '82 head. '82 was cleaned up at the factory and has higher compression. Trying to decide if I should buy the '82 head or hold off and look for one from '83+.

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Have you seen this before?

members.tripod.com/gpz_rider/technical/FAQ2000.htm