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zxr 750 engine swap

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zoutmax
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PostPosted: 22:07 - 23 Jul 2011    Post subject: zxr 750 engine swap Reply with quote
Hi,

I have a zxr 750 j2 92 restricted to 100 hp,
hard to de-restrict i am planing to do an engine swap.
What will be the most powerful engine who will ft ?
Can a zx9 engine fit ?

thanks

zout
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0ddball
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PostPosted: 23:17 - 23 Jul 2011    Post subject: Reply with quote
Yeah, the engine from a zx9r B model is what you want.
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zoutmax
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PostPosted: 23:23 - 23 Jul 2011    Post subject: Reply with quote
0ddball wrote:
Yeah, the engine from a zx9r B model is what you want.


The Kawasaki ZX-9R 'B' series from 1994 to 1997 has same engine fit ?
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CaNsA
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PostPosted: 23:29 - 23 Jul 2011    Post subject: Reply with quote
Why is it hard to de-restrict?
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0ddball
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PostPosted: 23:33 - 23 Jul 2011    Post subject: Reply with quote
zoutmax wrote:
0ddball wrote:
Yeah, the engine from a zx9r B model is what you want.


The Kawasaki ZX-9R 'B' series from 1994 to 1997 has same engine fit ?


Pretty much. It needs a bit of jiggery pokery with the front mount but it goes in easy.
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zoutmax
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PostPosted: 23:44 - 23 Jul 2011    Post subject: Reply with quote
CaNsA wrote:
Why is it hard to de-restrict?


The valves are smaller, am gonna try a model K/L (unrestricted) CDI,
the bike model k make 121 hp same but unrestricted engine, want my 20 HP or more back Smile gonna try cheap see how it goes with unrestricted CDI,it will still be restricted at the valves, i may go for an unrestricted model K/L cylinder head...or better swap for a zxr 900 B engine as 0ddball say it will fit. If CDI does not improve at all..

Last edited by zoutmax on 00:24 - 24 Jul 2011; edited 4 times in total
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zoutmax
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PostPosted: 23:54 - 23 Jul 2011    Post subject: Reply with quote
0ddball wrote:

Pretty much. It needs a bit of jiggery pokery with the front mount but it goes in easy.



What do you mean by " jiggery pokery with the front mount" ?
I do not want land up in welding home made mount, I look for a proper engine swap.
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CaNsA
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PostPosted: 00:09 - 24 Jul 2011    Post subject: Reply with quote
Fair doos,

no restriction in the back of the speedo like the imported 400's?
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zoutmax
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PostPosted: 00:17 - 24 Jul 2011    Post subject: Reply with quote
CaNsA wrote:
Fair doos,

no restriction in the back of the speedo like the imported 400's?


Speedo ? you mean RPM meter switch? Does not look like there is a RPM switch, the engine does not cut at high RPM but just loose 20 hp because CDI and valves are restricted, i guess carburetor idem....
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Barry_M2
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PostPosted: 09:44 - 24 Jul 2011    Post subject: Reply with quote
The J was never restricted as such, it was just built to make 100bhp. No restricters were ever fitted to limit power.

There were no restrictions in the CDI, no restrictions via the speedo and no restrictions in the carbs. The valves are NOT smaller, they are the same on all engines from J through to the M, and even the ZX9 B motor has the same size fitted too. The J cylinder head has no restrictions at all. Again it is the same across all models. There was a slight variation of heads from the K to L models (they are stamped #1 & #2 under one of the inlet ports. But these modifications were nothing major.

You will not be able to fit the K or L CDI as the connectors are totally different to the J.

To raise the power of a J in line with the K and L, you need to change the cams for K or L items, and also the pistons as they are slightly higher compression on the newer models.

Or yes, you can put the ZX9 motor in fairly easily, I've done this a couple of times. You need to slightly drill out the two front mounts as the ZX9 mount on the head is about 5mm out, and also grind a few mm away on the left front frame mount so the oil line does no foul it. It's very easy! Wink
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zoutmax
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PostPosted: 22:36 - 24 Jul 2011    Post subject: Reply with quote
Barry_M2 wrote:
The J was never restricted as such, it was just built to make 100bhp. No restricters were ever fitted to limit power.

There were no restrictions in the CDI, no restrictions via the speedo and no restrictions in the carbs. The valves are NOT smaller, they are the same on all engines from J through to the M, and even the ZX9 B motor has the same size fitted too. The J cylinder head has no restrictions at all. Again it is the same across all models. There was a slight variation of heads from the K to L models (they are stamped #1 & #2 under one of the inlet ports. But these modifications were nothing major.

You will not be able to fit the K or L CDI as the connectors are totally different to the J.

To raise the power of a J in line with the K and L, you need to change the cams for K or L items, and also the pistons as they are slightly higher compression on the newer models.

Or yes, you can put the ZX9 motor in fairly easily, I've done this a couple of times. You need to slightly drill out the two front mounts as the ZX9 mount on the head is about 5mm out, and also grind a few mm away on the left front frame mount so the oil line does no foul it. It's very easy! Wink



Hi Thanks for the advise i was wondering because of this :
https://homepage.ntlworld.com/webzxr/zxr750r/History/History.html

"The ZXR was overhauled and the "J" models were born. The Js were deliberately restricted by Kawasaki to 100bhp (and are hard to derestrict), but had very good midrange"

Hard to derestrict mean to me the engine has been reduced in power, they say from model k same engine unrestricted :

"A Race version (superbike omologation special - "K" model) was also built, but in limited numbers. This was called ZXR750R (or ZX7R in the US). The race version had the same frame as the J models, but it sported 39mm Keihin Flatslide carburettors, full power engine, close ratio gearbox, alloy tank, fully adjustable suspension front and rear, single seat and was 5kg lighter than the J models."

"Full power engine" mean to me J model engine but unrestricted for model k.

Someone told me they have smaller valves and CDU is restricted, cam too i guess.

Then you say that if i change the cam and a slightly higher compression will give me back my 21 hp lost from my model J to a model K ?
From the document carburettors model k are bigger :
sported 39mm Keihin Flatslide carburettors,
Then that also has to be changed.

I strongly think that model j is restricted :
https://homepage.ntlworld.com/webzxr/zxr750r/History/Specifications/91_zxr.html

100bhp (Restricted for fear of an Europewide HP limit which never happened - good midrange as a result)

I also think that a model K cdu will fit on my model J.
I buy on ebay a model K cdu, i will let you know ho it goes.

Then i will go cheap first and see if model K CDU give more power than the J model,the model K connector and even the whole CDU look exactly as my model J, on the model J/K manual they even put model k cdu on the electric schema for model J/K but specify it is the model K reference, that meant to me J/K has the same electrical beam and probably same connectors because the electric schema for model J/K is the same, only the CDU is different as model J is restricted, i wanted to check the part number on my model J but is erased Sad
If i need cylinder and head replacement i may go for a 900 engine as it seems not too hard to fit, thanks for the advice.
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0ddball
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PostPosted: 23:42 - 24 Jul 2011    Post subject: Reply with quote
You ask advice then argue against it. I know a fair bit about zxr's and Barry knows even more. He's had more 7's than some people have had bikes full stop.

But let us know how the K cdi goes.
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zoutmax
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PostPosted: 08:37 - 25 Jul 2011    Post subject: Reply with quote
0ddball wrote:
You ask advice then argue against it. I know a fair bit about zxr's and Barry knows even more. He's had more 7's than some people have had bikes full stop.

But let us know how the K cdi goes.


Yes i argue on facts :
https://www.technischedaten.com/view/kawasaki-zxr750-%28r%29-%28zx750-j,k%29-service-manual-ger-by-mosue/59202841/1os5sgllmkp96c8h9b4h/

Look page 221 of the manual for model J/K same electric beam, i will not agree that it has different connectors, you can see the model J and K CDU on the picture.

There is 2 CDU model one for the model J that i suppose is restricted, the other for model k, otherwise why a special model for the J ?
As both bikes are supposed to be almost the same as the manual is for J and K models.

This is a fact no more, whatever experience he has.
If i ask advices, am not gonna take them as granted if i have the proof they are wrong.
Do you mind if i stay on my idea, unless you have a document showing that CDU and connectors are not the same for model K and J.
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0ddball
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PostPosted: 08:50 - 25 Jul 2011    Post subject: Reply with quote
lol. You ask a question, you don't like the answer so you decide to ignore it and carry on regardless. Par for the course on this forum, you'll fit right in.

Your money, waste it how you like.
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Barry_M2
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PostPosted: 08:56 - 25 Jul 2011    Post subject: Reply with quote
You asked for help and I gave it. I've stripped, rebuilt, tuned and modified a lot of ZXR750 motors, you just need to have a look in my proflie to see what I have done to the engine in my own 750M.

The K model came out as a holomogation model for World Superbikes, which is why it came with FCR's (as opposed to CV's on the J (these carbs are NOT restricted)) and the close ratio gearbox, ally tank etc... You are assuming they built the K engine and then restricted in and put it in the J! Wink

Like I mentioned above, nothing is 'restricted' as such in the way you are thinking. It's not just a quick snip of a wire like on the import 400's etc... to bump up the power.

If you want to see more power, replace the pistons, replace the cams, and if you can find a set, buy the FCR's from the K model.

All you would gain from replacing the CDI anyway would be a higher rev limit. And if you were to raise the rev limit, you'd also need to put in the dual valve spings replacing the single spings in the J. The hard thing to do would be actually finding a K CDI!

An easier way of getting more power would be to find a L engine and fit that rather than chainging parts in the J engine, its almost identical to the K but does not have a close ratio gearbox. The J carbs will fit straight on too.

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zoutmax
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PostPosted: 09:08 - 25 Jul 2011    Post subject: Reply with quote
0ddball wrote:
You ask advice then argue against it. I know a fair bit about zxr's and Barry knows even more. He's had more 7's than some people have had bikes full stop.

But let us know how the K cdi goes.


This is to referring to the manual J/K model they look like this in the manual :

model J CDI (no mounting holes) 91 model J1 :
https://www.ebay.co.uk/itm/Kawasaki-ZXR750-ZXR-750-91-CDI-/150523575399?pt=UK_Motorcycle_Parts&hash=item230be77c67

Model K CDI (mounting holes) :
https://www.ebay.co.uk/itm/Kawasaki-ZXR750-K-L-CDI-Box-all-good-/160405144212?pt=UK_Motorcycle_Parts&hash=item2558e44294

The connectors must fit, mine has no mounting holes as model J2 91, i will let you know soon i receive it.
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zoutmax
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PostPosted: 09:26 - 25 Jul 2011    Post subject: Reply with quote
Barry_M2 wrote:
You asked for help and I gave it. I've stripped, rebuilt, tuned and modified a lot of ZXR750 motors, you just need to have a look in my proflie to see what I have done to the engine in my own 750M.

The K model came out as a holomogation model for World Superbikes, which is why it came with FCR's (as opposed to CV's on the J (these carbs are NOT restricted)) and the close ratio gearbox, ally tank etc... You are assuming they built the K engine and then restricted in and put it in the J! Wink

Like I mentioned above, nothing is 'restricted' as such in the way you are thinking. It's not just a quick snip of a wire like on the import 400's etc... to bump up the power.

If you want to see more power, replace the pistons, replace the cams, and if you can find a set, buy the FCR's from the K model.

All you would gain from replacing the CDI anyway would be a higher rev limit. And if you were to raise the rev limit, you'd also need to put in the dual valve spings replacing the single spings in the J. The hard thing to do would be actually finding a K CDI!

An easier way of getting more power would be to find a L engine and fit that rather than changing parts in the J engine, its almost identical to the K but does not have a close ratio gearbox. The J carbs will fit straight on too.

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Then i agree here, this is why i open this thread for an engine swap, i think that something is different in the cylinder head (cams or valves), as you says the cylinders could be too, and the carbs are smaller, then i think to replace the engine instead working on it by changing cylinders and head, a 900 engine look good to me as you guys said it must fit without big modifications.
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zoutmax
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PostPosted: 10:34 - 25 Jul 2011    Post subject: Reply with quote
0ddball wrote:
lol. You ask a question, you don't like the answer so you decide to ignore it and carry on regardless. Par for the course on this forum, you'll fit right in.

Your money, waste it how you like.


I follow advice when they are right, CDU stuff is wrong to me.
I can see it with the documentation, so i will not follow it, now i agree on the explanations on the engine, so i will follow an look for a ZX-9R 'B' series from 1994 to 1997 or a zx7 model K or L. I think there is no further questions needed, i got my answers.

Thank you for all, this thread can be closed as i will not argue on your attitude.
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chris-red
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PostPosted: 10:44 - 25 Jul 2011    Post subject: Reply with quote
I have a Triumph Speed Four, it has the same engine as a TT600 barring a couple of modifications, my bike make 12bhp less.

Is it restricted? No of course it isn't it is tuned differently for more midrange.


Also claiming facts from a website that starts https://homepage.ntlworld.com


Laughing
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zoutmax
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PostPosted: 11:19 - 25 Jul 2011    Post subject: Reply with quote
chris-red wrote:
I have a Triumph Speed Four, it has the same engine as a TT600 barring a couple of modifications, my bike make 12bhp less.

Is it restricted? No of course it isn't it is tuned differently for more midrange.


Also claiming facts from a website that starts https://homepage.ntlworld.com


Laughing


Let play with the words if you like.
The Zxr model J has been tuned down to 100 hp because of the 100 hp law which has never been applied.
Normally this bike is about 120 hp, now because of the law they made up a bike with 100 hp, i call that restricted.
Otherwise this bike will have done 120 HP like others, but because the law it is not like this.
I am not talking about same engine with different hp mounted on different bike with engine modification for meet the bike needs.

Yes the address of the website look funny but the contents are more reliable than what i can find here.

What do you try to bring here with your post ?
Something useless ?
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chris-red
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PostPosted: 12:22 - 25 Jul 2011    Post subject: Reply with quote
zoutmax wrote:
chris-red wrote:
I have a Triumph Speed Four, it has the same engine as a TT600 barring a couple of modifications, my bike make 12bhp less.

Is it restricted? No of course it isn't it is tuned differently for more midrange.


Also claiming facts from a website that starts https://homepage.ntlworld.com


Laughing


Let play with the words if you like.
The Zxr model J has been tuned down to 100 hp because of the 100 hp law which has never been applied.
Normally this bike is about 120 hp, now because of the law they made up a bike with 100 hp, i call that restricted.
Otherwise this bike will have done 120 HP like others, but because the law it is not like this.
I am not talking about same engine with different hp mounted on different bike with engine modification for meet the bike needs.

Yes the address of the website look funny but the contents are more reliable than what i can find here.

What do you try to bring here with your post ?
Something useless ?


Calm down mate Laughing


Did they ever make a 120hp ZXR J model? If not then what is it tuned down from?

Tuned down does mean it is a restriction. Is the fact my bike doesn't come with a full blown race exhaust system, and big bore valves mean it's restricted?
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Fortuna
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PostPosted: 12:43 - 25 Jul 2011    Post subject: Reply with quote
I'm quite sure you're chasing rainbows if you think there is a 120BHP J model.
A ZX-7R with flatsides, full pipe system and filter barely makes that (model P).
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Barry_M2
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PostPosted: 13:21 - 25 Jul 2011    Post subject: Reply with quote
chris-red wrote:

Did they ever make a 120hp ZXR J model? If not then what is it tuned down from?

Tuned down does mean it is a restriction. Is the fact my bike doesn't come with a full blown race exhaust system, and big bore valves mean it's restricted?


I think that's what he can't quite get his head round. The engine was built to make 100bhp, it was never 'de-tuned' as such. Then for the race Holomogation version (the K) they tweeked the motor up a bit and added a few fancy parts, raised the rev limit 500rpm with a new CDI, etc etc....

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0ddball
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PostPosted: 13:22 - 25 Jul 2011    Post subject: Reply with quote
The irony is your newbie quoting websites that anyone who's been into 7's for years will know backwards and have read inside out. Webzxr isn't 100% correct, could have worded certain things better and hasn't been updated for donkeys. Still a decent source of info though.


Here's another one, www.redmonkey.com/7r .Why not pop by and give them the wealth of your knowledge. Though i'd wind your neck in a bit or they will not be as nice as we have.
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Barry_M2
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PostPosted: 13:35 - 25 Jul 2011    Post subject: Reply with quote
zoutmax wrote:
Let play with the words if you like.
The Zxr model J has been tuned down to 100 hp because of the 100 hp law which has never been applied.
Normally this bike is about 120 hp, now because of the law they made up a bike with 100 hp, i call that restricted.
Otherwise this bike will have done 120 HP like others, but because the law it is not like this.
I am not talking about same engine with different hp mounted on different bike with engine modification for meet the bike needs.

Yes the address of the website look funny but the contents are more reliable than what i can find here.

What do you try to bring here with your post ?
Something useless ?


Ok, here is what happened.......

Kawasaki decided to redesign and update the ZXR750H with the J model, and done so with a completely new bike.

They built the engine hoping to get a jump on the other manufactures with the imminent 100bhp law for European bikes.

They built the K model (based on the J) as a Race Holomogation for entry into World Superbikes, giving it a close ratio gearbox, FCR's, fully adjustable suspension, ally fuel tank and.... a few extra tweeks in the engine to give it more power (cams, pistons, valve springs).

The 'Euro 100bhp law' never came into effect and Kawasaki replaced the J and K models with the updated L.

The L model used an almost identical frame (now with a hole cut for ram-air) and used the engine out of the K but without the close ratio gearbox. So in effect, the J engine was never used again, because it was only built to make 100bhp.

The M model is the race holomogation version of the L model and is again uses an almost identical engine to the K & L, but again uses the close ratio gearbox, FCR's, etc...

I hope that clears things up for you Smile Thumbs Up
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