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Discussion Starter · #1 ·
Hey guys I've got a few technical questions and inquires, I have searched and wasn't able to find the answer to any of questions at hand. I'm hoping that someone will know the answers to these questions I have.

So I currently have a 88 ZX750R F2 (GPX750R) and I'm looking to do some upgrades and hoping that I am able to improve a few things on her. I absaluty love my bike minus the few things that I am not the biggest fan of.

- not the biggest fan of the off set size tires 16"front and 18" rear
-also not a big fan on the size and profile of the tires either.
-and not that I don't like the suspension setup, but I do believe that it could have bin way better then it is.
Those are the 3 biggest things that don't please me 100%.
So I am able to get my hands on a 1991 as well as a 1992 ZX750R parts bikes for a half decent deal. But before I commit to purchasing either one of these machines, I would like to know what would be interchangeable from either the 1991 or 1992 over to my 1988.
QUESTION 1
i have noticed that my fork seals are begining to leak on my 88 and knowing that the seals are going to need to be changed, I was wondering if the front forks from the 91 or 92 would be a direct fit?
The only difference that I know about here is my 88 is a regular fork as both the 91 and 92 have inverted forks. Or if the forks arnt interchangeable would the entire front end be able to be swapped?
QUESTION 2
the rear suspension and swing arm. Would the rear shock and swing arm be interchangeable at all?
I only ask about the swing arm because at the end of the day I would prefer to be able to have the same size rim and tire on the front and back instead of the 16" and 18" I currently have. As well I'd love to have a jig bigger tire profile on the rear as well. A 190 is alot better then the 140 I am currently running.
QUESTION 3
the engine would these engines be interchangeable at all one being the 88 f model and the other 91-92 being the k model?

Any info on this that anyone may have would be greatly appreciated.
Thanks in advance
 

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There is very little (if anything) common or interchangeable between these bikes. The only ZX7 that has some common parts is the H1/H2 (1989-90). Even these will be different in a lot of ways.
As for forks and suspension, anything can be modified to fit but the time, effort and cost is usually the deterrent.
 

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Discussion Starter · #3 ·
There is very little (if anything) common or interchangeable between these bikes. The only ZX7 that has some common parts is the H1/H2 (1989-90). Even these will be different in a lot of ways.
As for forks and suspension, anything can be modified to fit but the time, effort and cost is usually the deterrent.
I kinda had a feeling but I was kinda hoping lol. But as for the front forks changing the entire head unit and bearing wouldn't they just easily go together
 

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No. Totally different. Besides, the frame is so flimsy on those early ones, if you could do what you are thinking would flex like a wet noodle. You would be much better off finding a newer bike.
 

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I would buy the 91&92 parts bikes if they are actually genuine K models though. Better to try making one of those into a bike.
 

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Discussion Starter · #6 ·
No. Totally different. Besides, the frame is so flimsy on those early ones, if you could do what you are thinking would flex like a wet noodle. You would be much better off finding a newer bike.
My 88 is far from a weak flimsy frame it is a solid steal frame just saying
 

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Discussion Starter · #7 ·
No. Totally different. Besides, the frame is so flimsy on those early ones, if you could do what you are thinking would flex like a wet noodle. You would be much better off finding a newer bike.
And besides even if it were to flex how would a set of front forks and rear swing arm flex my frame?
 

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You asked for advice and 57x offered. The steel frame of the F model 750 has a lot more flex in it than an aluminum beam ZX7 frame. ALL chassis and suspension components are designed (by Kawasaki) to work together. Changing the swing arm or forks (which are more robust and rigid) from a ZX7 could put stresses into the frame that it cannot handle. You may end up with an ill handling bike or a cracked frame. It may not be an issue but it would be an expensive endeavour to trial.
I would simply buy the 2 ZX7s and build a good bike from that.
 

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So I currently have a 88 ZX750R F2 (GPX750R) and I'm looking to do some upgrades and hoping that I am able to improve a few things on her. I absaluty love my bike minus the few things that I am not the biggest fan of.
My 2c.

Sounds like your bike means alot to you. If the nostalgia is strong enough, restore it to stock. Enjoy it the way it was made originally. Display it proudly in your living room and ride it on special occasions. It will not be cheap to source all oem parts however.

And besides even if it were to flex how would a set of front forks and rear swing arm flex my frame?
Metallurgy, construction and geometry play huge roles in motorcycles. Race teams change entire frames and swingarms just to increase or decrease flex. A street bike from 1988 may not have reinforced stress points. Not to mention the rate of development was incredible. Just 3 years meant machines were massively improved and totally different . Increasing the rigidity of one area transfers forces to another. You could in theory break your frame just with changes you suggested.

57x may not be the most diplomatic, but that guy has more knowledge about these bikes than most of us put together.
If you need a demonstration of his skills, refer to this build. Idiots don't build bikes that nice.
Scott Russell Muzzy ZX-7R M Superbike Restoration

I also agree with him, find a bike that rides to your expectations, and leave the 88 model alone and enjoy it for what it is.
 

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Discussion Starter · #10 ·
My 88 is far from a weak flimsy frame it is a solid steal frame just saying
I appreciate your input it just made no sense to me on how the frame could be flimsy. So since I'm being told that you are the most knowledgeable about these bikes. Can I ask you about changing my rear tire as I do need a new set of rubber what would be the harm in going from the 140 to a 150 or possibly a 160?
 

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Discussion Starter · #11 ·
You asked for advice and 57x offered. The steel frame of the F model 750 has a lot more flex in it than an aluminum beam ZX7 frame. ALL chassis and suspension components are designed (by Kawasaki) to work together. Changing the swing arm or forks (which are more robust and rigid) from a ZX7 could put stresses into the frame that it cannot handle. You may end up with an ill handling bike or a cracked frame. It may not be an issue but it would be an expensive endeavour to trial.
I would simply buy the 2 ZX7s and build a good bike from that.
Any input I'm taking and learning from. Just didn't make sense to me how a steel frame could be weaker then an aluminum frame. Can I ask you about up sizing my rear tire from the 140?
 

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If the 140 is the stock width (I’m not familiar with this model year spec), I would stick with it as it will be the best option for handling. If you go wider (150-160...), you may have clearance issues with the swingarm or fender. Also, putting wider tires on narrow rim changes the profile and pulls the beads in closer than they were designed. Going up to 150 is probably going to be okay as long as you have clearance.
Personally, I stick with the sizes Kawasaki R&D determined since they spent all the money on development.
 

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Discussion Starter · #13 ·
I've seen some post where people have got a 150 on and there is enough room for a 150. What would be the worst possible outcome even if it does fit?
 

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If you install a 150 (assuming no clearance issues), there will not be any issues. Going up to a 160 may create an issue.
Personally, I stick to the recommended sizes that Kawasaki has determined work best. JMO.
 
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