kz1000 and gpz questions

i was studying the 78 kz parts diagram and noticed you guys only have to deal with two bearings on the ends of the crankshaft as opposed to all the stupid bearing inserts i have to go through with my crank. this seems like an advantage in simplicity makes strength. am i correct? im thinking about after this 750 project is over, maybe getting into the bigger Z's. but im also curious as to the gpz and when they stop being kz engines and start becoming their own. i know the 81 and 82 gpz 1100 were the same as kz's. or at least thats what i thought. im wondering if the newerish (96) are less reliable than our kz's and less rugged. not as overbuilt, ya know?

so, what years are the best to aim for as far as engineering goes for the kz1000 engines go. and then are gpz's kz engines or are they more like detuned ninjas more aimed at the touring crowd. i know they got competent reviews for their power and comfortable seating. this entices me but so does the allure of owning a bike that is notorious for being bull hide tough, the kz1000. so whats what then???

bump

73-80 900/1000 motors are all pretty hard to break even under severe use;)

The GPz 1100 engines are basically KZ 1000J engines or at least J bottom ends and will fit straight in a J/ELR 1000 frame - they can be put in a standard KZ1000 frame too, but it will require some fab work, the motor mounts are slightly different.

The 81/82 GPz 1100 engines are pretty much the same, the major difference is the heads/injector mounts - 81 GPz has the injector bodies sitting in the head above the intake, which caused some heat problems, 82 Gpz has the injectors sitting in the intake manifolds and has a a few more ponies than the 81, factory specs for the 82 say around 109 hp (at the crank). Both 81 and 82 GPz 1100s use 17mm wrist pins and shim over bucket.

83> GPz 1100 (UniTrak) are the last of the big air cooled Kaws and is by many considered the best engine Kawasaki built (speaking of vintage engines mind you). 83> GPz is rated at 120 hp (at the crank) and use 18mm wrist pins and shim under bucket.

There is also some slight differences in the clutch between the 81/82 (5 bolt clutch) and the 83> GPz 1100 (6 bolt clutch), but on the outside they´re physically the same and interchangeable.

All of the old GPz 1100s use a HyVo/multiplate cam chain and sliding blocks whereas the old KZ1000s prior to the J use a single roller cam chain with idler sprockets.

Post edited by: OnkelB, at: 2007/08/04 18:05

:pinch:

Post edited by: OnkelB, at: 2007/08/04 18:02

seems like the gpz engines are the way to go then. just as reliable as the kz's, or with all that power did there come problems as well?

Not really, as far as I know most of the problems were with the fuel injection - 81s had a heat problem with the injectors sitting in the head, this was solved by moving the injectors to the carb manifolds on the 82, but I believe there were still some issues with the FI electronics being somewhat unstable.

If I were you I´d get a J frame, put an 83 GPz1100 engine in it, rip the FI off and replace it with a set of Mikuni BS34 or similar - that´s how my 82 1100 is set up, it has 58,000 miles on the clock and is running strong as ever.

In my opinion and limited experience with the GPZ1100/KZ1000J, they were not even close to the reliability of the pre 1981 KZ1000s. I only owned one though, a 1982 GPZ1100 I bought new and admittedly rode the crap out of it covering over 24,000 miles in 17 months. I could have covered more if it wasn't for 2 top end rebuilds under warranty. It was darn well shot at 24,000 miles. Cycle World magazine did a long term test on the 1982 GPZ1100 and pretty much had the same experience as I did. "Did not age well" was the only thing I remember. The fuel injection could be problem, and mine was, but that was just the tip of the iceberg on this bike. I hate to say bad words about it, because it really was my favorite bike to ride I've ever had and still have frequent dreams about owning one again. Too bad it wasn't really that great.

dang.

i wonder how the newer mid nineties gpz's hold up??

all this input is really helping future decision making. thanks guys! i just hate how hard it is to get a kz1000 when you want one without breaking the bank or driving across the nation...

a 1000J engine holds up well to abuse, mine took a great beating befor and after the big bore kit (self install) with the only problems being wiring, plugs, jets and the occasional part rattling off because of the ridged rearend.

if you can built a smallblock chevy, you can build one of these with your hands behind your back.

i also belive the 82-84 1100 has bigger intake runners and is reffered to as the "bathtub"

note: i want a 83-83 gpz1100 engine soooo bad just for the head and buckets.:evil:

There is one more caveate that is extremely insignificant (unless you're a professional drag racer) the 1984 GPz1100 had slightly steeper valve angle and is the 'racers choice' for dragster dudes.

Your comparison to newer (ie '96 GPz) bikes is an apples / oranges comparison. The newer GPz1100 is based on the ZX1100 Ninja which is a liquid cooled, 4 valve, plain bearing crank-shaft motor. The big 'Z' Kawasakis and the GPz/J bikes are all roller-bearing air-cooled two valve motors and are juuuuust about indestructible. The newer bikes are (sort of) the same when it comes to being indestructible. However, when you want to pump more power thru these bikes there are different paths to take for each of the two different motor styles. The KZ/J/GPz motors need their crank shafts welded and then after that the mods vary, reinforced clutch-hubs and hardened back-cut transmission gears are about the most you need to do for almost all power applications for strengthing purposes. The ZX motors have a design flaw which causes a problem on (#3???) bearing on the crank shaft. A simple oil gate re-routes oil in the cases to fix this. BUT, as this motor is water cooled big pitson kits are extremely limited.

Maybe I went too deep, but the short version is that all the motors (new and old) are strong and reliable. "KZ" bikes (the bikes that this site is predominantly dedicated to) all have the air cooled two-valve motors; '83-'84 GPz1100s are air-cooled but have a ZX1100 'A' and 'B' designation; the ZX1100 Ninjas are the 'C' and 'D' models, the GPz1100 of '95-'96 are the (you guessed it) 'E' models.

I have an '82 GPz1100...but I bought it already blown up.:blink: I'll be picking up an '83 GPz1100 this winter and I'll be doing the above mentioned "fuel injection to the curb" modification before I even start it...but that's another story.:whistle:

thanks, thats exactly the info i was looking for. i think i kinda misunderstood when people say some bikes are tougher than others. its not so much in stock form that some bikes are weaker, but more so when you want to start tinkering and changing the formula that you have to worry about things breaking and going to ca-ca on you. the 70s kaws have a sort of mystical allure about them to me, being practically unbreakable. sadly, youve kinda taken that away. HA! i kid. but this info helps broaden my choices on my next project after i get this thing all put together.

im thinking about finding more info on racing small honda inline fours through that vintage racing association. any one know anymore about it? i cant afford the new age stuff, so why not do it vintage. just an idea im kicking around in my head.