zr7 motor in KZ750

well, in a nutshell, it fits!





funny that when i went searching here, never seen one done before.... maybe because in the US the zr-7 was not sold that much? here in europe they were quite popular for a long time. you can get well kept samples for as little as 1100$

the original 80K miles motor in my 750 was actually OK until it developed a leak in the cyl base gasket, well it's time to pull out the zr7, 15K miles, hardly run-in motor i found in a swap meet fot 200$

so, yes, it fits, but quite a lot of stuff had to be modified, definitely NOT a drop in and drive. took a weekend + a week of after work nights to finish, spacers on the lathe, etc.

but also quite a lot of reasons to do the swap: much fresher motors, primary chain tensioner (way quieter), improved sealing in the half moons area, rack and pinion clutch actuator (like half the effort of the kz750 at the lever), sturdy 8mm exhaust studs, comes stock with oil cooler, improved auto cam tensioner, bigger oil pump... enough?

dont know how interesting it is for most 750 KZR-ers, but if you have questions, shoot.

and forgot, the best bit, it runs now like a brand new bike!

Very neat and great job to go through the effort to not just figure this out, but to also take a stab at doing it!

You mentioned the oil pump which is key, many may not be aware that you can actually swap in a ZR7 oil pump into a KZ750/650 motor. I know for a fact that the 750 motor works, and 99% certain that it fits the 650 as well since those are nearly identical. Great upgrade if you already have the engine out

Brett

well, i diid fit an zr7 pump to my gpz750/810 vintage racer ages ago... still believe it's one of the reason it did 5 racing seasons withtout trouble !

from my racer build

kzrider.com/forum/2-engine/410994-gpz750...ing?start=120#429788

Not that I'd ever do it, but I've been wondering if it was doable. Is that a 1980 KZ750E?

martin_csr wrote: Not that I'd ever do it, but I've been wondering if it was doable. Is that a 1980 KZ750E?

yep, it's a 1980E, first year for the 750 model, now with a 2004 motor

Thanks. What were the biggest fitment issues? I would have guessed the motor mounts would be the same, since the ZR engine number begins with KZ750EE. I'm assuming yours does.

Thanks for posting TG
Very interesting. Looks like a really good fit

Not that i'm planning anything major at the moment but great to know what can be done

Fitting the ZR7 motor is the same as doing a GPz motor swap
into a 650/750.
As for the ZR7 oil pump it fit's all KZ650/750 and ZX750 motor's.

zukdave wrote: Fitting the ZR7 motor is the same as doing a GPz motor swap
into a 650/750.
As for the ZR7 oil pump it fit's all KZ650/750 and ZX750 motor's.

Dave, especially with your history in the racing field and putting these motors to their limits and then finding the next weakest link I had a question for you on this... I have heard time and time again on the 750turbo site that the ZX750E motor had notorious poor oil pressure and flow performance, which is why they do so many upgrades on the oiling to prolong the life of the engines. My understanding is that the engines while not identical are very very very similar to the KZ650/750 and ZX750 motors we are discussing. Does that mean that the non-turbo ZX750 and KZ650/750 engines have the same oil performance weakness too?

Inquiring minds want to know :woohoo:

Thanks,
Brett

I've never heard of any oil related problems on the KZ650 engines. Mine has a mere 60,000 miles without ever having any oil problems, but Ronkz650 put 168,000 miles on his KZ650 without oil related problems. Ed

650ed wrote: I've never heard of any oil related problems on the KZ650 engines. Mine has a mere 60,000 miles without ever having any oil problems, but Ronkz650 put 168,000 miles on his KZ650 without oil related problems. Ed

Absolutely believe that and know of the bulletproof reputation of these engines. That is why hearing about the severe oil issues on the Turbo version confused me. I know that there are some differences between the engines but I would struggle to imagine that they are so dramatic as to cause this level of concern, does that make more sense Ed?

Thanks,
Brett

Makes sense to me. I wonder if the turbo 750 pushed things a bit beyond the design level of the oil pumps used in the 650 and normally aspirated 750 engines. For example - the KZ650-C1 made 64 hp while the 750 turbo GPZ makes 112 hp (see 1st link below). With that much oooomph that turbo 750 is probably putting a lot more stress on the internals. Some heavily modified turbo 750s put out as much as 282 hp! (see 2nd link below) I wonder what they use for pumping oil through those beasts; I can't believe they use the stock pump, so maybe there's a unit that could be easily used in the street turbo bikes if the stock units aren't up to the task. Ed

www.motorcyclespecs.co.za/model/kawasaki...pz750_turbo%2083.htm

www.750turbo.com/forum/viewtopic.php?f=9...cfe43309e10ecd320fd3