KZ650 vs. KZ750-4 Heads?

Hey, I was wondering if anyone knew these dimensions for a KZ750-4. I'm trying to determine if my head is suitable for my 810 build or if I should get a 750 head.

Intake port outside diameter ~36mm
Combustion chamber diameter ~61mm

Just need to see those. If anybody can help that would be awesome.

I would get a ZR750 (Zephyr) head. I believe the valves and ports are bigger on that head. Plus it has more cooling fins for MUCH better cooling. They are not that hard to find and the combustion chambers will be the right size for the piston domes.

No eBay APP ID and/or Cert ID defined in Kunena configurationHere is one.

I'd need to get the whole engine for that to work. My engine doesn't have the same cam chain system as that.

Not true you just have to do the same mods that we do when we put J heads on a KZ. Otherwise get a mid 80s ZX750 head.

It actually looks like the top idler would fit that. Theres absolutely nowhere to mount the top idler on a zx750 head, at least not that I can see. I'd have to machine a notch in the bottom for my cam roller though.

I have a spare zr750 head if you need any dimensions or detailed pictures from it.

In the meantime, does anybody have these dimms?

I am pretty sure that reborn650 did this with his. I think he got 750 barrels bored to 810 and I know he used his original 650 head as I saw it one summer evening in his garage and remember he had the 650 cam chain rather than the hyvo chain used on the 750.
That was quite the bike - a 650 with 810 displacement. I cant remember what he did for carbs. He may have used the Mikunis from the 650 and jetted up. I can remember velocity stacks. He has'nt been here in a while. HOpe he ws'nt arrested. That thing was a screamer :laugh:
Try a search. There was a big thread on this about 2 years back.

T-dub. I'll get you the dims in the morning if noone else has posted by then. You are gnna want to go with the 750 though, the valves are a bit bigger. this is the route I went w/810 as was suggested by many and it works excellent. I cant compare it to the 650 head-810 but maybe i should give it a try one day this summer. you probably alrady know all this, but the cam sprockets off your 650 onto the 750 camshafts. and as you said, make sure the head you get will accept the idler (i know the 81 kz750 head i got fit the 650 idler) . hope this helps, and i'll get back 2 in the AM.

speak to larryc he will be able to tell you the potential in the different models heads, he is very knowledgeable when it comes to what the head needs to flow for a certain configuration and if the head can be ported to that level.
Very clever man :blink:

These questions arose when Larry asked them haha. He doesn't really know the diff between the 650's and 750's. These were his concerns I'm trying to address. Larry's gonna be porting the head and thats why I want to figure this stuff out. I might get a ZR750 head like okatar suggested, or I might get a kz750 one. I think it'd be interesting to have a zr750 head on it, such an old bike with a eight year old head would be funny. I am leaning towards a 750 head though, seems to be the correct route in any case.

Thanks pburnhamb.