Hi I'm Frank and writing from USA, I don't read or write any German so hope you can help me out with my modification.

I got myself a classic Ninja 750r/ ZX-750F 87-90 model last year (not new to riding, just been away from 15 years, hence my choice in old bikes) and enjoy it but struggling to keep up with my friends on latest toys.

The 750 got a stock geometry of 27d Rake, trail 97mm/3-7/8” which handle like a brick, then there is the 16” front wheel which make the bike feel like a brick with a shaky front so I decides to do something about it.

1. I replace the rear air shock with a 1” longer rear shock off a SV650, Stock was 12.18” long and new one is 13” long and it raise the rear about 1.5-1.75”

2. I swap the stock 3.5” x 18” rim 140/70-18 rear with a 88-90 ZX10 4.5”x18” rim 170/60-18. Even though new tire is 10% lower in tire profile but I do noticed a change in bike height (its higher) due to larger rubber?

3. I swap the stock front wheel 2.5”x16” rim 120/80-16 with a 88-90 ZX10 front 3.5”x17” rim 120/60-17. The new rim/tire also drop the front profile about a ¼”-1/2” compare to stock.

I just finish the mod and test ride it locally around couple blocks and noticed a new bike below me. Handling become so easy that it scare me like I can think the bike into a turn without much effort at the bar compare to stock.

I wonder if I have gone too far? I hear somewhere that if you raise the bike 1” either way, you’ll change the rake by 1 degree, does that sound right? If that’s the case then I figure I have drop the rake from 27 stock to 25? Anybody out there have knowledge regarding bike geometry please give me some feedback as I have not take it to the freeway or test it in the canyons but I want to make sure what I did is not too extreme or safe to ride. Thanks in advance.



Front Wheel



Rear Wheel



Ninja 750r-1



Ninja 750r-3



Rim



Modified /Stock right



170/60-18 Left, 150/70-18 Right



Ninja 750r ZX-750F Twin

Hello Frank,

welcome as first member of the USA.
Where do you live, because i have to attach you to the membermap.

I change your attachments soon, because html-code isn`t allowed here, so for pictures please use [img}..img-url..[/img]

If you want to use it here in english please try to set the languidge to english in your "Profil". There is an option in "Benachrichtigungen und das Verhalten des Forums ändern".

Perhaps here is something interesting for you, you have to translate it:

http://www.fietes-gpx.de/

For reading here please use a translator, such as google or something else.

We hope to hear from you soon again

Achim

Hy Frank,

Why have you copied my GPX ???? (Only meant as a joke )
If you look at the "gallery", you see that we have the same style.
Warm welcome here in the forum, nice greetings from Austria.
greets
K4E (Wolfgang)

Hi Achim & Wolfgang, Thanks for the warm welcome :-) I'm in Los Angeles, California, USA. Not many Gpx here still in good shape after 20+ years. I like the fact that there are so many dedicated owners there in Germany and you guys still keep your bikes in such a nice shape. I got the inspiration to modify my rims from a picture I found in your pic gallery so I want to share it you guys that it can be done with little work of course.

We have no such club here in USA for GPX bikes so consider you guys vary lucky :) How many GPX owners/members are in Germany currently?

Cheers,

Frank

Nice that the sister of my lady driving around in LA.
In Austria, there are not so many GPX, in Germany there are a few more.

I have 3 pieces of GPX in my family and Achim also has some standing in the garage.
Most people here in the forum have now more than one GPX "in the barn." We are a group of "crazy".
For real-depth technical assistance are the members "Achim" and "Fiete" certainly the "elite".
greets
K4E (Wolfgang)

Greet you also here! I am curious whether you create it also to X meetings this year.
Outside board engine to your GPX and over the big pond!
Greeting from northern Germany
Heiko

Also greetings from the real Brunswick in Lower SaXony. Nice to hear that there is even one in USA who is keepin' up our ol' lady over there. Nice and clean bike that you have, gratulation. Interesting paintjob, did you do it by yourself?

In my baby, I have a wheel with the front 3.00 x 17 - tires 120/70-17. I have a rear wheel 4.50 x 17 - tires 170/60-17. The handling after tuning is totally new. It's almost like the current bikes. I have heard of the conversion with the ZX10 wheels. The wheels are a good match for our bike. I do not believe that you have gone too far. I think that's OK.

By the way: nice bike

Hi all, would be happy to see you guy at the X meet if I can find a way to get my bike over the ocean :)

Fiet: I agreed with you that the handling of the bike after modification is totally new/different and I have to learn to ride my 750 over again, its soo easy to turn now that its kind of scary/fun at the same time. I was afraid that installing a 1"/25mm longer shock would change the geometry too much...stock 750 is 27d Rake and new is 24.5? Your Project 09 have a zzr600 shock...how long is the shock? Do you know what Rake angle your bike have now?

I was going to find a Ninja 500/EX500 front wheel like you then I notice that Euro model have dual disc on front, USA model only have one disc so I can't use that bike's wheel. I think 91 ZX-11 rear wheel is 17x4.5" and 92 ZX-11 is 17x5", if I want to use a 17" rear rim the ZX-11 wheel is my next option. For me, the rear wheel swap is easy and front is more difficult as I have to change out the bearing and machine down the wheel spacer.

Hi!

My brother's GPX was modified by a previous owner...
He mounted rims from a Bimota, which are really hard to find, but fitted without much modification...
On the front there was a 17" x 3,5" with a 120-17-70, original GPX brake calipers and discs...
On the rear there was a 17" x 5,5" with a 170-60-17, also original calipers and disc...
AFAIR the 5,5" rim was the widest possible, because there were only a few milimeters between chain and rim...
There were also only a few milimeters between the 170-wheel and the original GPX swing arm (don't know the correct word)...

So 5" should fit, but i wouldn't go wider than 170 with the original swing arm...

If you want to use a wider wheel, like a 180, another option would be a ZZR 1100 (IIRC from the C-Model) swing fork, rim, brake and (not a must) shock...
Sometime somewhere in the web i found a howto, but now i don't find it anymore...

schubl

sorry - what is shock?

The front wheel of EX500 with dual disc you get from us is not easy. Many people build it into the GPZ900.

Normal it means: "Stoßdämpfer"


Aber ich kann den Zusammenhang nicht ganz verstehen ??

lg
Wolfgang

Meint ihr meinen Zusammenhang?
Manchmal steh ich ein bisserl auf der Leitung beim englischen...
Und da unser US-Kumpel schon shock geschrieben hat, dachte ich er wirds verstehen...
Auf Deitsch: Irgendwo im Netz hab ich mal ne Anleitung gefunden, wo einer Schwinge, Felgen, Bremse und Stoßdämpfer von ner ZZR1100 eingebaut hat, nur find ich die nimmer...
In die Originalschwinge bringt man meiner Meinung nach nichts breiteres als einen 170er...

Oder bin ich schon wieder mal nur paranoid?

schubl