Hi All, my name is Frank and I just join this forum and hope to get some help from members regarding my project. 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 Ό”-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.

 

Welcome to the forums!!! Can't answer your question but it sounds like a great project!!! Post some pics when you get a chance...this sounds like a question for Dragone...

 

Welcome To Kawasaki Forums.
They're a lot of Good Members Here(Like Odimus) and they will do there Best to Help You out with Your Questions. Sometimes It Takes A Little Longer Then Others. So, hang-in there.
+1 on the pic's

 

Welcome fj. Just a few quick thoughts. A.) Your old bike will not keep up with a new bike, period. I speak from experience. B.) If you raised the rear AND lowered the front, you definitely will turn without much effort. Be careful. Your changes aren't TOO radical, but still, be careful because what you may not notice at low speed may become a wobble of death at road speed. (Yes, I know you're not a novice.)
Other members may have better insight than me.
Glad to have you aboard! Gear up; stay safe.

 

 

 

 

 

use your http link with the mountain looking symbol in the reply box. Nice looking ride. Not real happy with those front forks for adjustability and known issues though. Water damage was the big thing as well. Love the ride, looks great. You would have to google the rake and trails. Penske and some of the other suspension suppliers have good charts as well. welcome to KF and thanks for the pics

edit: sheesh, I am still learning how to ride and work on the rides!

 

On the newer bikes if you put shorter dog bones on the rear it makes the bike turn in quicker. It sounds to me that when you changeg the shock it raised the back end, same concept as a dog bone swap. By changing the rim/ tire size you will have a higher mid section on the tire. All of the changes made will make the bike turn at speed efortlesly but i would be carefull with your counter steering until you are used to its new lean angle. also you can get wobble at speed when aplying the front brakes if its rake is to low. Anyone else agree with these findings?