Top end cylinder differences between 1981 and 1982

Replacing my old cylinder head and the cylinder. I broke a camshaft bolt in the cylinder head and because i tightened the cylinder head too tight, i cracked a piece of metal off the cylinder close to the chain tensioner. So i need both the cylinder head and the cylinder.

I found a part bike a 1982 KZ750H. I have a 1981 KZ750H LTD. I notice some differences in the 1982 cylinder head where it looks more square than the 1981 head. Does anyone know if these heads are compatible? They seem to line up the same but I noticed on the top of the head some extra bolt holes.

Anyone know what they bolt up to? When lining up the valve cover those extra bolt holes don't seem to be used. On the 1982 head, those holes aren't there. I do notice some other differences in the cylinder block where the Rear chain guide sits. I want to know if this block can be used, or will I have to buy the Rear chain guide and the Front chain guide from the 1982 engine because of the different designs. When I purchased the 1982 KZ750H, part bike someone had already taken the rings, chain guides off the bike. I just need the top end of the motor to complete my bike.. Can someone shed some light on if I can use the top end off this bike? I have posted some pictures below.. Thanks in advance..

Im going to take a shot...not sure....but one could be a GPZ and one a KZ head?

I agree one does appear to be from the GPZ and the other from a KZ. You should be able to use them but will need the cam chain guides/wheels.

I wonder if its the differant style cam chain parts that theyre made to fit,hyvo versus bicycle stye chain.
The kz1000s made the change from 80-81,not sure when smaller bikes did it

The extra holes in the first head (four holes in the center of the pic) are the mounting holes for the top cam chain idler used in a single roller cam chain setup (as Jim says) - this type of head was used on some early 750 fours (80, 81, maybe veary early 82), basically a reworked 650 casting.

Heads will interchange for your purpose in as much as you can use the first head with a hy-vo cam chain, but you can't use the second with a single roller setup.

Btw, the 650s made the transition from single roller to hy-vo cam chain around 80-81, all 750 fours including the GPz had hy-vo cam chain.

It is my understanding that the Hy-vo chains were first used on the 650s in the non US market in 81 and then in the US market in 82.

gd4now wrote: I agree one does appear to be from the GPZ and the other from a KZ. You should be able to use them but will need the cam chain guides/wheels.

gd4now thanks for your response.. The head that has the 4 extra holes is my original head. My bike is a 1981 KZ750LTD. I have the all the parts including the front chain guide and the rear chain guide, pivot, and both rubber dampers. attached is a diagram of the CAM CHAIN ASSEMBLY..

The part bike I picked up looking at the sticker is identified as a KZ750H. ATTACHED IS PICTURES OF BOTH STICKERS. I understand these parts are interchangeable. I am asking can I use the same front and rear chain guides from my original setup or will i need to buy the chain guides to fit the GPZ head, or are they the same? Looking at the cylinder heads you can see the differences. It was mentioned the Head i have is a GPZ head, (one without the extra holes) is it possible the PO took a GPZ head on this bike or did the 1982 KZ models come with it.





Please elaborate.. Thanks.

gd4now- Also the donor bike didnt come with the camshaft caps... I understand these caps to be machined with the head.. Can I use my other camshaft caps from the KZ on the GPZ head? The GPZ also didnt come with the buckets or shimms or camshafts. I was thinking just move all parts from the KZ over to the GPZ head..

Will this work?

OnkelB wrote: The extra holes in the first head (four holes in the center of the pic) are the mounting holes for the top cam chain idler used in a single roller cam chain setup

OnkelB- thanks for your response.. My KZ setup didn't use a top chain idler. So it sounds like I wont need to use those 4 holes anyways..(the head with the 4 holes is damaged which came from my KZ750LTD) I am trying to use the one without the 4 holes.

I just want to know if the head (the one without the 4 holes) can be used on the KZ750LTD motor with the cylinder head using the chain guides which came with my bike (KZ750ltd) ? Will i need to purchase diffrent guides or can I use my front and rear chain guides.
I just put the rear chain guide unto the slots and it seem to fix perfectly..

Without the cam caps, I'd be real leary of using that head, you may get lucky, and you may not. If I understand correctly your original head has a broken bolt which is stopping you from using it. If that's the case, I'd have it removed or do it yourself. That way you know everything is right for your setup.

Les

les holt wrote: Without the cam caps, I'd be real leary of using that head, you may get lucky, and you may not. If I understand correctly your original head has a broken bolt which is stopping you from using it. If that's the case, I'd have it removed or do it yourself. That way you know everything is right for your setup.

Les

Thanks Les.. I've tried removing the broken bolt.. I have been unsuccessfull in removing it.. I have also drilled into the aluminum trying to remove it. I decided to look into replacing it. So the option of keeping it does not exist. I purchased the parts bike for $100 so its of great hope to use these parts.

Will it not work? You mentioned Luck. Where does luck play into all of this? If i just throw the damaged head back in and not use the bolt to hold down that section of the cam, I dont think this would be a good ideal.. Very unlucky as a matter of fact.. Excuse my ignorance. I am just thinking transfer everything over.. Am i overlooking something. Where does "Luck" come into play at?

Basically I was doing a rebuild of my KZ750 LTD. when rebuilding the motor I broke a cam cap bolt in the #1 (outter) hole. Also cracked my cylinder block by over torquing the rear bolt. I now need the top end of motor to get it back together.

I'm at the point of figuring out if I can use these two parts (Cylinder head and block) off the donor bike. I am expecting to use for right now those two parts. The motors (bottom ends) look Identically alike.

The donor bike cylinder head is missing the valve buckets, shims, both cams, and cam caps (aluminum cover to hold down the cam). Sorry i don't know what its called..

I am asking if I can just transfer the hardware from the damaged head over to the donor head? So that I am back to where I left off, so to completely get the bike back together. Afterwards, I can start cheeking for valve clearances. Thanks for your response in advance..