KZ750E cylinder head options

Just off of the top of my head, these are the major differences between zr-7 heads and cylinder block from the kz/gpz/zx/zr750 heads and cylinders in case any body is considering doing this swap.

1. Cam chain tensioner is zr-7 specific. The shape of the tensioner where it bolts into the cylinder block and the length of the tensioner is very different. ( because zr-7 uses different lower cam chain guides) Cam chain itself is exactly the same as kz.
2. As noted before, the zr-7 head uses a bolt on upper cam chain guide Instead of being in the valve cover. You will need this! This and also the totally different cosmetic shape of the head means you have to use the zr-7 valve cover.
3. The zr-7 cams are totally specific to that head!
They have a “disk” cast into the cam that acts as a Side thrust plate. Kz/zr...etc heads have specially molded cam caps that limit side-to-side cam thrust. Zr-7’s do not have those style cam caps. YOU CANNOT USE AFTERMARKET OR ANY OTHER MODEL CAM IN A ZR-7!

There are surely other diffrences, but those are the only ones I can think of. Other than that, the combustion chambers are the same and the heads and blocks will easily bolt onto a earlier style motors.

Food for thought....

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hugo wrote: I do not believe you would have any problem with the Zepnyr head. If there is any different in flow it would be insignificant. As far as I know, the only truly factory 'hot rodded' in KZ750 series was the GPz, with higher compression and hotter cams.

.....I have used KZ750 head gasket on Zephyr 750 and they are the same. Yes, of course, you would need the Zephyr valve cover, but not necessarly the cross wedge Zephyr tensioner. I use a manual one, not because the auto ever failed, but because the manual makes top end maintenance a breeze. To me a autotensioner is for those who do not understand tensioner, and do not perform maintenance.

..................it is little more risky, of course, because more uncertainties, but I think the ZR-7 head would work too, as long as camchain length is same.

So the GPZ heads would be straight replacement as well? But "hotter" cam meaning more top end or across the entire rev-range. I am not looking for top-end power I am more for a good beefy mid. But again I might be able to find more low-milage GPZ heads here in Europe - so it may be worth the effort. Or just drop in the cams from my old head.

Daftrusty wrote: Just off of the top of my head, these are the major differences between zr-7 heads and cylinder block from the kz/gpz/zx/zr750 heads and cylinders in case any body is considering doing this swap.

1. Cam chain tensioner is zr-7 specific. The shape of the tensioner where it bolts into the cylinder block and the length of the tensioner is very different. ( because zr-7 uses different lower cam chain guides) Cam chain itself is exactly the same as kz.
2. As noted before, the zr-7 head uses a bolt on upper cam chain guide Instead of being in the valve cover. You will need this! This and also the totally different cosmetic shape of the head means you have to use the zr-7 valve cover.
3. The zr-7 cams are totally specific to that head!
They have a “disk” cast into the cam that acts as a Side thrust plate. Kz/zr...etc heads have specially molded cam caps that limit side-to-side cam thrust. Zr-7’s do not have those style cam caps. YOU CANNOT USE AFTERMARKET OR ANY OTHER MODEL CAM IN A ZR-7!

There are surely other diffrences, but those are the only ones I can think of. Other than that, the combustion chambers are the same and the heads and blocks will easily bolt onto a earlier style motors.

Food for thought....

Thanks a lot! That was very good and detailed knowledge. Exactly what I was looking for. As I am looking for a direct replacement and not a winter-project, I think the ZR-7 heads are out of the question for now.