550 Head identification question

Hi. Looking at heads on the ebay for my 81 KZ550A2 and found THIS one:







It's listed as a rebuilt head off a LTD, but I'm thinking it's gotta be off a ZX550 GPz...

there's no hole for the tach cable bolt, and it appears that the hole for the cable itself is not drilled through all the way, and there's no tach gear on the exhaust cam. Seeing as the zx550s had electronic tachs, this would make sense. Also, referring to LOUDHVX's camshaft info, it would appear to have GPz camshafts because they both have the cast grooves to the right of the sprockets.
I've asked the seller about it but haven't heard back yet.

So, anybody know if this is indeed a ZX550GPZ head, and if it could possibly work on a KZ550A2?
They both appear to use the same head gaskets, but valve part #s are different.

I know I'd at least have to switch to an electronic tach, and use my cams, if they'd fit.

I'd appreciate any advice.
Thanks.
Al

I see now that the head could be from a '83 or '84 LTD, but the cams definitely appear to be GPz cams

Yes, they are some type of Gpz or Zephyr cams.
There are two types:
1) 82 KZ550H1 gpz, 83 KZ550H2 gpz, ZR550B zephyr, all the same grind as 81 KZ550D1 gpz but without tach drive.
2) 83 ZX550A1 gpz, 84 ZX550A2 gpz. Different grind, and different cam drive gear on the intake.

You could determine if they are ZX or not by looking at the intake cam sprocket. My valve train page shows the details on what to look for.


The head itself can be:
82 KZ550H1 gpz
83 KZ550H2 gpz
83 KZ550A4 standard
83 KZ550M1 shaft-Ltd
83 KZ550F1 spectre (shaft drive)
84 KZ550F2 shaft-Ltd (took over the Ltd name)
84 ZX550A1 gpz
85 ZX550A2 gpz

All of those use TK26 carbs except the ZX, which use TK27 carbs. The intake ports may be a tiny bit bigger for the TK27 carbs, so that may be a difference on the head if it is ZX, but sorry, I don't have the dimensions.

I think it will fit on to your KZ550A motor because it uses the same head gasket, but I have no confirmation on this. (The valve cover and gasket are different, so you would need to find that as well.)

I know on the J motors, they ID the Factory Cams by the Cast In Grooves. Its in the service manual, has the cam specs, and grooves for ID. Maybe the 550 manual has it also?
If that is a GPZ head, and Cams, you will get a power boost running it with the cams. Finding a rack of the bigger carbs would also help. But like you say an electronic Tach would need to be fitted. Depends on what your looking for, stock replacement or a power boost.

Thanks guys. I hadn't even considered the carb size. It's probably a little above my financial means at the moment for everything that would be involved. Would there be any valve/cylinder clearance issues ?

almous71 wrote: Thanks guys. I hadn't even considered the carb size. It's probably a little above my financial means at the moment for everything that would be involved. Would there be any valve/cylinder clearance issues ?

There shouldn't be any valve-piston issues since the KZ550A motors have lower compression pistons. I think they are dished as opposed to the GPz's which have a flat piston with valve notches.

The valve timing etc. can be found in my signature link about valve trains.

The original gpz uses the same carbs as the standard model. You can run the tk22 carbs on the later motors by notching the tk22 manifold mounting tabs. The spacing on the carbs is the same. The only issue is that since the manifolds would then have to span acroos a larger intake throat, there is slightly higher chance of vacuum leaks. But that is not too hard to remedy with gaskets and sealant etc.

Motor Head wrote: I know on the J motors, they ID the Factory Cams by the Cast In Grooves. Its in the service manual, has the cam specs, and grooves for ID. Maybe the 550 manual has it also?

I never found any mention of the grooves in the 550 manuals, but I did not look that hard. I have a bunch of various cams and found all of the gpz ones have the cast in grooves. I compared notes with several other gpz owners and non-gpz owners and their findings agreed.

The ZX gpz cams have the same grooves even though they have a slightly different grind.

All of the standard and Ltd models don't have the two grooves.

Thanks Loud.
How about the exhaust spacing? Would my stock 550A exhaust bolt up ok? This refurbed head is still pretty appealing, but I'm worried about getting in even more over my head. I may just try to go with something closer to stock.

Exhaust shouldline up with no problem.

Thanks Loud, but I just noticed that the intake cam sprocket on that head has 3 sets of mounting holes...



So I guess it's from a ZX550. The guy said the cams are original to the head, but he didn't actually know what 550 it was off of. I can definitely take this one off the list now.