New Member, Seasoned Rider, New pipe Dream haha

Hi, my name is Jay, I'm 28 yrs old and ive been riding bikes since i was 9 and on the street for about 9 years. Ive had a few Z1000's, couple SRAD's and a couple older bikes. I joined up becuase i have a new interest--- Normally i build cars (engine/tranny swap into older cars such as LS motors, 6 speeds, big firebird fan) but now I'd like to try something new. My options this summer were one of 2, 1) go be lazy and buy a new or newish ZX14 and call it a day ---or--- 2) build a cafe racer from an old Kawi. I have chosen #2 and this is what id like to do:

Tomorrow im going to pick up a 79 KZ 750 twin, bikes all there, price is $375, my ideas for this bike are, front fork swap to latest style (zx6?), swing arm swap (zx6?), a mono cafe style fiber glass seat, mono rear shock (zx6? R6?) and... this is the most important one of all, remove and replace the 750 twin with either an 05+ 750cc FI or 1000cc FI engine, ZX10 perhaps? Now i did alittle research on here before i became a member and i am familiar with what needs to be done concerning structural integrity of the frame, my friend and i have an a pretty decent shop and we both weld, i have a few questions in mind about the engine/tranny swap

Are there any major mods needed that would negate this swap, making it a complete waste of time? Should i try a 600cc FI engine instead? Questions for me? Comments?

Thanks,

Jay

You sort of lost me here. You plan to get a KZ750 twin and change the forks, swingarm, and engine. Changing the engine to a modern one will require swapping out the electrical system and involve serious frame changes. Changing the fork and swingarm will also lead to changing the braking system. You will no doubt also change the handlebars and seat from the stock KZ750 twin seat which is not cafe-ish at all and no doubt remove or at least highly modify the fenders and side covers.

I'm not trying to be judgmental, but when you are done there is nothing left except possibly the fuel tank (if you decide not to change it) that is remotely similar to a KZ750 twin. So why not buy a newer bike and use that as the base platform from which to make your changes? At least then you would have a frame that has the structural integrity to handle the increased horsepower/torque of the newer engine and an electrical system that matches the engine. If you want, you could just put a KZ750 fuel tank on the newer bike; after all, isn't that sort of what you will end up with if you do the build the way it is envisioned? Ed

I have to agree with Ed here. It would be like taking Ford body and mounting it on a Chevy frame and motor and calling it a Ford. Hope this does not squash your enthusiasm. KZ's are awesome bikes but when that much is changed its no longer a KZ.
What ever you decide to do I'm sure will be great. In the end your the one that needs to be happy with the build. Just make sure you sell the parts you don't use so the rest of us can keep the old KZs on the road.

What they said. Except take the car analogy one step further. It's closer to putting a Ford steering wheel in a Chevy and calling it a Ford.

If you do it send me the motor! It may be low on HP but it's high on the fun factor.

kaw-a-holic wrote: I have to agree with Ed here. It would be like taking Ford body and mounting it on a Chevy frame and motor and calling it a Ford. Hope this does not squash your enthusiasm. KZ's are awesome bikes but when that much is changed its no longer a KZ.
What ever you decide to do I'm sure will be great. In the end your the one that needs to be happy with the build. Just make sure you sell the parts you don't use so the rest of us can keep the old KZs on the road.

Hey people have been shoving chevy drivelines in fords long before most of us were born! :woohoo:

I dont see where he says he is building kz What I read is he needs a hobby and has a kz to start with.
I am thinking he will call it a Jaykawa when he builds it. :laugh:

Building a bike can be as theraputic as any shrink and probably cheaper in the long run.
125.00 an hour 3 times a week for a year yeah a Jaykawa is probably less expensive.

with that said Congrats on your recent purchase Let the bikes character decide where you go with it modern stuff on these old bikes makes all the difference in the real world building something unique is
a labor of love unlike putting a 454 in a pinto chances are when your done (if you complete it) your the only one who loves it.

If you have a zx6 laying around that is ridable in allot of peoples minds you will destroy 2 motorcycles if you dont have one laying around then that level of changeover would be strictly a vision that most wont understand but then again very few understand converting a perfectly good motorcycle anyway.

if you were chopping up an early Z1 i might cringe as the 750 twin guys are now. but the reality is its your bike, your vision, and i am here to help if you have any questions or need any imput

as you will see there are threads and projects that are several years old with soome pretty cool builds heppening and i am sure there are more than that that have been put in boxes and lost in storage lockers landfills and bone yards.

Cheap price to pay for the mental clarity DR Kawasaki will give you
good luck with your build and post some pictures dont let the neysayers keep you from going to therapy

im a newbie so ill take this in stride, but i think youve got me wrong. heres my idea i have centered around..

2.bp.blogspot.com/-42DbITeDlXI/T4umHyirr...iddleton+%281%29.jpg

i didnt want to upgrade to a newer engine (whatever FI engine will fit with least mods) without upgrading the suspension.

im hoping i havent offended kawi purists?

I don't think it's a matter of upsetting purists as I doubt the bike you're buying is an untouched, pristine stock example. It is more a matter of practicality. A KZ750 twin frame is not a particularly good choice for the starting point for building a bike with a modern, FI engine. The frame must fit the engine as far as mounting points etc., because the engine structure cannot be modified to fit the frame. Changing the dimensions of a frame to fit the engine can be done (in fact I have done this before out of necessity), but in the end you must end up with a frame that is configured to physically accommodate the engine, and you really should strive to end up with a frame that can manage the horsepower/torque of the engine or you may suffer serious consequences. So rather than re-invent the wheel and try to convert a KZ750 twin frame into the equivalent of a modern frame that was intended to support the modern engine; it makes sense to me to start with the frame that matches whichever engine you select and use that as the starting point for your project. After all, I suspect the object of this project is to end up with a motorcycle that can be ridden and ridden safely, so my recommendation is to start with the basic engine/frame structure rather than trying to take on the rather complex engineering task of designing a frame. Otherwise you may end up becoming discouraged and scraping the project (we have seen this happen before when over-ambitious goals were set without the necessary resources and skills at hand). In any case - good luck. Ed

BTW, I may be mistaken but the Honda in your link appears to have a Honda frame that matches the engine. Notice similarity to Honda frame below:

Boy, sure are taking the long way home! Just a thought, have you considered a modern v-twin powerplant? A spirtbike motor, but atleast still sticking with the twin thing. It would also maybe be worth your effort to have your current engine refreshed(media blast,bored,etc. Etc.) And put modern ignition/fuel injection on it? Either of those two options would yeild a more manageable power output. A zx-10 motor will positively shred that frame.

Thanks Ed and Tom, i have considered a newer twin and yes, i did see the pic i posted was a CB, i just like the concept. I discussed with my buddy about what we can do and he is recommended the same things---for now. I'll be doing researching and parts picking in the next week and will post pictures of whatever progress I make. thank you for the input.

There is nothing you can do to make that frame contain 200 hp and modern tyres. Nothing!

Back in 1981, Kawasaki introduced the then new KZ1000J and GPZ1100 with all new frames. Frames with racing in mind. A frame good enough to give Kawasaki 2 Superbike titles. But even gusseted by chassis experts like Muzzy and others, it still flexed badly when asked to tame 140 horses. And the tyres, much less grippy than what street bikes have today, still had enough grip to bend the frame visibly out of shape, sending rider and machine into weaves strong enough to make seasoned sailers seasick.

The 750B frame is much weaker.

If you are destined to mix retro with 200 horsepower, do yourself a favour and start with a Zephyr 750. Or even better, a Zephyr 1100.

OTOH, you can make a very nice bike that handles respectably if you put let's say an ER-6 engine into it instead of a Ninja 1000. Or if your want a wailing four, an old Ninja 600 for the 1980s.

However, it's still your bike and your project and you will do as you see fit

Right. The KZ750 twin frame was designed to handle its 55 hp engine.