Kawasaki Motorcycle Forums banner
1 - 12 of 12 Posts

·
Registered
Joined
·
58 Posts
Discussion Starter · #1 ·
Hi!

I own an old beat upp gpz750 -83 which I am fixing for the summer season. I rode it last summer for a 1000 km and it is an oil-drinking smoking beast. So I am in the process of replacing the piston rings and valve seals.
Something I also noticed last summer was that the brakes are spungy and pretty much useless when it comes to stopping the bike. The front fork is a bit soft too.

Someone of the previous 19 owners crashed the bike and replace the front fork and brakes with one from a earlier year, probably from a 1982 GPZ750.

I was thinking about a few upgrades for the brakes and the fork. Progressive springs and thicker oil, 15-20 W, is planned. Also steelbraided brake lines and probably a new set of brake rotors.

But I don´t know how good the brake calipers and the brake pump are, is it worth spending money on spareparts that are just as good as original or should I be looking for a front fork from a newer bike?

So the questions I have are those:

1. Would the front fork improve enough to handle well with thicker oil and progressive springs? Or should I look for a replacement fork?

2. Are there any better fork from a newer bike that would fit my GPz with minor modifications?

3. The brakes calipers are single piston, would it be better to look for used twin piston calipers that would fit my bike.
Also the brake rotors are they big enough?

4. Brake pump, simular question, good enough?

So in general I would appreciate any advice on how to improve the performance of the brakes and the front suspension. And since you are more experienced you may be able to tell if the original brake system would work fine if it was in good condition.

I just started riding bikes so I don´t need extreme high performance stuff, I wouldn´t be able to make use of it anyway. And my budget are limited ofcourse..

The aim is a well working working bike that I can try on the race-track once in a while. Not to compete, just to ride a little harder.

Hope you can understand my english, I am from sweden so it is not my native language.

Merry Christmas!

/Karl
 

·
itching to ride
Joined
·
2,238 Posts
Your english is fine. Better than some of us here in the usa.

The stock brakes are fine if you are not going to use the bike solely as a track bike. And even then they would do the trick but not as well as some of the more modern ones, if you can even get any to fit. But for your use I would say they will be more than adequate if you redo them. New kits for the master cylinders, new caliper seals, and new braided lines will make a world of difference.

On the front suspension if you go with new springs then maybe go with 10 or 15 weight oil first to see how you like it. 20 is pretty heavy for forks I think.

Just my thoughts and I am by no means an expert on brakes. There are more knowledgable people on this site and I am sure more will give their thoughts on the matter.
 

·
Registered
Joined
·
58 Posts
Discussion Starter · #4 ·
Thanks for your answers, I will follow your advice and stick with the stock fork and brakes. I will pull the brake calipers apart and make sure everything looks fine. And probably machine the brake discs to get rid of some groves if they are thick enough, since they are quite expensive to buy.

Are there any other modifications I should do now when I have the bike in pieces? I have thought about bracing the frame but I haven´t found any good description on where the frame needs reinforcements. I found a Gpz Modification FAQ but it seems that my bike already have most reinforcement they recommend so their tips are probably for earlier bikes.
If you have any ideas on the subject I would be glad to hear them.

Or if you know of any other modification that is worth doing you are welcome to share them.

/Karl
 

·
This space for rent
Joined
·
687 Posts
1999-2000 GSX750 front end and wheels. Forks will fit with just a bearing change and rear wheel has the same size axle as the GPz so you just need spacers. And mill the sprocket mount down along with getting an offset front sprocket to line the chain up. That will allow you to run modern 17" radial tires, and the forks are a great deal better than the stock GPz750.

That's the easiest swap I'm aware of.
 

·
Registered
Joined
·
58 Posts
Discussion Starter · #6 ·
1999-2000 GSX750 front end and wheels. Forks will fit with just a bearing change and rear wheel has the same size axle as the GPz so you just need spacers. And mill the sprocket mount down along with getting an offset front sprocket to line the chain up. That will allow you to run modern 17" radial tires, and the forks are a great deal better than the stock GPz750.

That's the easiest swap I'm aware of.
Thanks for the info! If I stumble over these parts cheap it would be a nice upgrade.

/Karl
 

·
Biker Chef
Joined
·
1,026 Posts
I changed the fork oil on my GPz to 15w, and put a 1-1/2 inch of PVC pipe on top of the springs to compress them a bit. The differance in handling was VERY noticeable, for the better. The front end dive under braking is not as pronounced as it was before the PVC spacers.

Also, BE SURE to take the swing arm off the bike and check all bearings and bushings, as well as the rear shock. I let mine go unchecked for 12,000Km, and this summer, before a planned trip, it gave out. The bearings were so dry, 2 had no rollers in them at all! Its an easy job to do, but takes a bit of time, but is well worth it. And if you need bearings, you can get them at a bearing supply store on the cheap.
 
1 - 12 of 12 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top