KZ700-KZ750 engine swap

I have an '84 KZ700 that smoked a piston due to a lean condition. I cannot find .060 overbore pistons and do not wish to pay $75 a piece for sleeves and then $500+ for the pistons from Wiseco. I have to re-sleeve as they do not make a kit for the KZ700, only the KZ750. My question is this: Will a similar year KZ750 motor drop right in place of the KZ700 motor? I found a KZ750 motor with good compression that is only minus the ignition and clutch. It was my understanding they just sleeved the motor down to create the KZ700 but nothing else was altered. Won't everything, head, clutch, ignition, header, carb bank swap across and the wiring also remain the same? It should drop right into place with my current mounts right? All I would really need to do is a stage 3 kit for the carbs for the additional displacement and header, right? Anyone? Anyone?

Bueller? Bueller? Frye? Frye?

If you want to do the job with less expense, perhaps you could buy a good used cylinder with matching pistons. The engine swap will work as the outer dimensions are the same if you go that route. You don't need to put a "stage 3" carb kit in or rejet in any way. 40cc displacement will make absolutely no difference. I think the only difference in the engines is a shade less than 1mm less piston diameter for the 700.

As far as I know, you don't have to resleeve if you want the 810 kit from Wiseco. You can just have your current sleeves bored out for the 810 kit...

If you buy a used cylinderblock with pistons from another KZ, Zephyr or ZR-7, you can put it on the KZ700 engine. Just make sure you don't buy someone else's rubbish...

The 750's equiped with Mikuni carbs use a 110 mainjet and the 700 uses a 105 mainjet.

The internals of the 700 carb are a tad different... different air jet size I think and different jet needle/needle jet. You can't just swap jets based on a small displacement size difference. If you took the carbs of a KZ1100, they are also BS34 and I think they have #127.5 mains. You could use them with the stock airbox and the #127.5 mains but if you put #110 mains or #105 mains, you wouldn't be able to pull redline even with a 700 engine as the internals on the carbs are suited to the main jet size.

Also be aware that not all BS34 carbs are the same. The 1000/1100 BS34's won't fit into the 700/750 carb holders because they are larger in diameter than the BS34's used on the 83-85 GPz750.

My impression is that BS34 identifies the series, and there are different sizes within that series.

I have a set of brand new .020 oversize GPz750 pistons taht I am thinking of selling to get money to buy an 810 kit myself.

To put an 810 kit on a 750 will cost at least $600, and probably more since you will probably have to do the head also.

And that's doing everything but the machining yourself.

Just off the top of my head:

Wiseco 810 kit $400-$450
Boring $160-$200
Gasket set $50

Then you find out the valve guides are bad and need replaced, so you have to grind the valves, plus buy new shims.

I hope to have this motor done by next spring, thankfully it's a spare motor

The 750 engine (if it is a 4 cylinder) you found should bolt right up, with no modifications. Just borrow the components from your 700, and it should work fine. Yes, you could do the 810 wisco kit, but my guess is that with boring and all that will be a ton more money than the used engine, right? I keep "finding" used bikes and engines on the local Craigslist, so I know they can be had for cheap. Its the shipping that makes the ones on eBay cost prohibitive.

I don't know where you are located but I saw this listed on Ebay in Michigan. Complete KZ 700 motor with only 6200 miles on it. Current bid is only $56.55 with 2.5 hours to go.
cgi.ebay.com/ebaymotors/KAWASAKI-KZ700-K...QQrdZ1QQcmdZViewItem

Better hurry and bid.

wiredgeorge wrote:

The internals of the 700 carb are a tad different... different air jet size I think and different jet needle/needle jet. You can't just swap jets based on a small displacement size difference. If you took the carbs of a KZ1100, they are also BS34 and I think they have #127.5 mains. You could use them with the stock airbox and the #127.5 mains but if you put #110 mains or #105 mains, you wouldn't be able to pull redline even with a 700 engine as the internals on the carbs are suited to the main jet size.

@wiredgeorge,

According to the KHI manual the KZ700 and the KZ750L have the same carb internals except for the mainjet whic h is #110 on the 750 and #105 on the 700.
Pilot jets and needle jets are the same. They list a jetneedle 4BE04 for the 700 and a 4BE4 for the 750 but I assumed they were the same.
The ZX750A has a different jet needle and needle jet, but also #110 main jet.

@edgeman68,
Congratulations on winning the engine on ebay!!!

Post edited by: Paling1, at: 2007/06/27 04:53

Steve, I think the outside diameter of the BS34 used on an 1100 is the same as a 750. The difference between the two, as far as carb holders, is the way the outside of the venturi is shaped. there is a small flat area, then a dip, then it goes to flat. The carb holder has a lip on the inside to accomodate the dip and provide seal. the dip part is quite a bit different on the 1100 carb compared to the 750 BS34. The diameter of either is about the same as is the CV34 which has its own profile. I have head that folks who use Mikuni BS34 when CV34s were installed will eventually have problems with the CV34 style carb holders. There are actually three styles of lip and eventually I will set up a page on our website to document this and show the actual shape of the lip so the correct carb holder is used... I think the bikes affected are:


These have type 1 lip on the venturi and require a certain carb holder P/N 16065-1135:
KZ1000J1/J2
KZ1000K1/K2 LTD
KZ1000M1/M2 CSR
KZ1000P1-P25
KZ1000R1 REPLICA
KZ1100/A1/A2 SHAFT
KZ1100 GPz
KZ1100D1 SPECTRE

These are type two P/N 16065-1132:
KZ650H2/H3 CSR
KZ700A1
ZN700A1/A2
KZ750E1/E2/E3
KZ750F1 LTD
KZ750H1-H4 LTD
KZ750L3
KZ750N1/N2 SPECTRE
KZ750R1 GPz
ZX750A1-A3 GPz
ZX750E1/E2 GPz Turbo

These are type three P/N 16065-1131:
KZ1000J3
KZ1000R2 REPLICA
KZ1100A3 SHAFT
KZ1100D2 SPECTRE
KZ1100L1 LTD
ZN1100B1/B2 LTD
ZX1100A1/A2 GPz

To all who replied: thank you.

Gringo-I did get the motor and thanks for the E-Bay listing

Wiredgeorge-In swapping everything over from my 700 to the 750, carbs included, how could you think I would not need a stage kit? With the header (and I did fail to mention the airbox elimination) I would have to up the fuel delivery or I am going to end up with the same lean run hole in the piston that put me here in the first place.

Paling-Yes you do have to re-sleeve if you want to run the 810 kit in the 700 motor. It will not leave enough in the cylinder walls to be viable. I tried going that route first. Either sleeves or 750 jugs were needed and the sleeves are $75 a piece from Wiseco and the machining is outrageous.

Once the motor arrives and I get it in I will let you know how it all works out. Supposedly the motor has good compressioon and less than 7000 miles on it. My bike only had 14000 when the piston went. I bought it with the header, Dyna ignition and stuff already installed and assumed that the previous owner knew enough to jet the carbs. My assumption is proving costly.

Again, thanks to all

I'm glad to see somebody from here got it. That looks to be a really nice engine and you got a good buy on it as well. If it would have been just a bit closer I'd have probably bid on it, why I don't know, I don't need it and at the moment I don't have anything to put it in but hey when did that ever stop me. It sounds like it is the perfect solution to your problem, be sure to keep us updated with your progress.

edgeman68 wrote:

Paling-Yes you do have to re-sleeve if you want to run the 810 kit in the 700 motor. It will not leave enough in the cylinder walls to be viable. I tried going that route first. Either sleeves or 750 jugs were needed and the sleeves are $75 a piece from Wiseco and the machining is outrageous.

Hi Edgeman68,
Is the outside diameter of the 700 sleeves smaller then the outside diameter of the 750 sleeves?
I've heard the 750 sleeves will fit in a KZ650, so I can't imagine the outside diameter of 700 sleeves being different from the 650 and the 750.