GPZ Head on KZ

I have a couple of issues here. I bought this 1982 kz750 H3 LTD with a GPZ750 head on the KZ750. This brings up at least one problem, the Tach doesn't work. I was told that the GPZ head supports a digital tach and the KZ head a Mechanical Tach. I am not 100% sure what is meant by that but I assume that the GPZ tach is all "done" through the wireing harness. I bought a 1980 GPZ750 Tach off ebay (for $10) and am now wondering whether or not I should try to install it as a replacement for my KZ750 Tach...

The other issue is the head gasket. Am I correct in assuming that the head gasket for the GPZ750 is the same as the gasket for the KZ750 since the head was a "bolt on"? Should I get the GPZ gasket or the KZ gasket? It does leak and I'd like to get it finished before the summer gets here.

Thanks

how ironic, this is exactly the project im working on myself right now. im sure theres other out there too that will have input for you though. the gpz tacho will need to run off of one of the coil wires so it gets that pulse so it can represent the rpms on the gauge. the tricky part about this (i have the same model and year as you) is that there are three plugs coming off the original ltd gauge cluster whereas theres only one coming off the gpz. so now if you want to go the full distance with this, you need to obtain a wiring diagram from both the 82 750 (they are year specific so you must try to get the exact year and model for both diagrams) and whatever year gpz you got the gauge off of. from what i understand (as ive yet to do it) is you need to track each wire and see what each one does and plug them together accordingly. and yes the gaskets are the same due to the fact that the heads are identical except for the small differences about the tach worm gear hole and the mild porting job on the gpz heads. man, if steell reads this he'll be so proud...

Actually, I am not sure the 80-82 gpz's had the electric tach. The one that I run is from an 83-85 gpz. Not hard to hook up, but you will need the right part.
Check archives for wiring diagrams for this swap.

Bdog

the other option is you can have the boss drilled so you can run a mechanical tach.
wish i can find a gpz750 head for $10!
the gpz cams also do not have the worm gear on them for a tach so you will either need to find somthing like kz700 cams or a nice set of aftermarket if you want a mechanical tach.

I'm pretty sure the electronic tach was first used on the Uni-Trak (83-85 GPz750) models, I believe the 81-82 was mechanical.

I'm only going by what I was told by the PO. I can't find a spot on the GPZ head for a mechanical Tach. Or...it may have been sealed up...I'll have to strip the thing down and look more closely...

chrismcd68 wrote:

I'm only going by what I was told by the PO. I can't find a spot on the GPZ head for a mechanical Tach. Or...it may have been sealed up...I'll have to strip the thing down and look more closely...

I dont think you will find anything. I doubt the factory would go through the bother of machining a hole only to plug it because it wouldnt be used. that being said, you could drill it yourself and get different cams (ones with the worm gear) and run the mechanical tach, but I would just get an electronic tach. an aftermarket one at that. there have been some members here with them(with led displays and lots of cool features). I have been thininking about putting one on my 650 if the thing ever gets finished:P

The 1982 GPz750 used an electric tach, as does the 1982 Spectre 750 (KZ750-N1) and most likely the Spectre 1100.

Find a tach from a Spectre! It's the same size and shape as your stock tach, bolts right up and takes a signal from your coil.