KZR's Bikes of the Month for 2024

GPz750 R1 (1982) fixing up

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23 Mar 2017 00:54 - 23 Mar 2017 01:05 #757448 by HeavenlyMachines
GPz750 R1 (1982) fixing up was created by HeavenlyMachines
I recently acquired this bike:



Plenty of cosmetic work to be done but I don't think it qualifies as a real restoration project. I want to get all mechanical right first.

I'd like to keep the spirit of Kawasaki design intact so no 'cafe' or 'bobber' or such. It's already a handsome looking bike!

So far I had:
- Fixed timing chain mechanism
- Fixed choke mechanism
- Fluids, filters, o-rings

Big tasks ahead:
- Put back the airbox
- Paint the tank
- Fix up brackets, rattles etc.

Let the good times roll...
gpzninja.blogspot.com.au
Last edit: 23 Mar 2017 01:05 by HeavenlyMachines.
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23 Mar 2017 01:02 #757449 by HeavenlyMachines
Replied by HeavenlyMachines on topic GPz750 R1 (1982) fixing up
Today I received my carb synchronizer. Made the job very easy.




A shipment of good quality bar-end came from the UK. It is $25 and heavy. You can also see the handgrip heater I installed from eBay. Very tidy compared to Oxford and works well too. Good stuff for $20.


Let the good times roll...
gpzninja.blogspot.com.au

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26 Mar 2017 03:05 - 26 Mar 2017 03:08 #757715 by HeavenlyMachines
Replied by HeavenlyMachines on topic GPz750 R1 (1982) fixing up
Managed to put in the stock airbox today. The bike came with spare carbs with stock jetting.

After putting them it's like a *completely different bike*. Idles smoothly and pulls really strong to red-line! The only think I miss is the roar of pod filters, but there is no way I'm using those anymore. A big bonus is I'm no longer breathing the oil fumes from the crankcase!



The start with choke was difficult. Not sure why so I might need to inspect the choke mechanism.

The filter is one of those 'K&N" so I have ordered a stock foam replacement.

Once all good, I will repaint it to black.

The rubber boots were hard so to rejuvenate I soaked them in 70% Xylene + 30% Methyl Salcylate for 6-8 hours. The boots swell but returned to original size.



Xylene was bought at Bunnings ($18) and Methyl Salcylate at Chemist Warehouse ($6).

Earlier I tried by just boiling them using Methyl Salicylate + water. But it did not work as the rubber would harden again when cold.

Let the good times roll...
gpzninja.blogspot.com.au
Last edit: 26 Mar 2017 03:08 by HeavenlyMachines.
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26 Mar 2017 04:57 #757719 by Nessism
Replied by Nessism on topic GPz750 R1 (1982) fixing up
The choke pick up tube goes down into a small passage in the float bowl. It's important to use a piece of wire in the pick up tube to make sure it's not plugged up, and make sure the passage in the float bowl is open as well. These passages love to plug up which renders the choke inactive on that carb because it can't get any fuel.
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26 Mar 2017 15:36 #757763 by HeavenlyMachines
Replied by HeavenlyMachines on topic GPz750 R1 (1982) fixing up
Thanks. I've been reading some carbs fixing in the forum too,

Are you referring to the following passage? I will check that they are clean.



When the bike is running and I pull the choke the engine runs rough which indicates that the mechanism work, But not sure how clean they are.

Let the good times roll...
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26 Mar 2017 15:42 #757766 by Nessism
Replied by Nessism on topic GPz750 R1 (1982) fixing up

HeavenlyMachines wrote: Thanks. I've been reading some carbs fixing in the forum too,

Are you referring to the following passage? I will check that they are clean.


Yes. Don't forget to check the tube as well.

zeus.mtsac.edu/~cliff/storage/gs/Mikuni_...Rebuild_Tutorial.pdf
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26 Mar 2017 16:03 #757767 by HeavenlyMachines
Replied by HeavenlyMachines on topic GPz750 R1 (1982) fixing up
Wow thank you. What a wealth of experience to help me through this!

And I just learnt to that these screws are not Phillips but 'JIS' ....! I've been wondering why my screwdrivers felt to pointy for these carb screws.

Let the good times roll...
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26 Mar 2017 17:53 #757773 by azman857
Replied by azman857 on topic GPz750 R1 (1982) fixing up
Looks like you got a good one to bring back. I put the engine of one in a Z650B frame. Enjoy yours.

I don't have a plan and I'm sticken' to it! '77 KZ 650 / 750 GPz custom project in progress
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26 Mar 2017 20:26 #757779 by HeavenlyMachines
Replied by HeavenlyMachines on topic GPz750 R1 (1982) fixing up
Yes it's in good form but it is also the most frustrating bike I've owned. It actually died on the freeway while doing a club ride with my wife !

But the biggest scare was when I found out the previous owner had missed putting a washer on camchain tensioner stop-bolt. Enough to jam the mechanism so it was running without tension!.. could have gone bang any moment especially that I've taken it for a fang twice and ridden it on the redline!

More learning I suppose...!

Let the good times roll...
gpzninja.blogspot.com.au

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28 Mar 2017 02:38 #757920 by HeavenlyMachines
Replied by HeavenlyMachines on topic GPz750 R1 (1982) fixing up
Well I took the bike to work yesterday and I was unable to start the bike. Even rolling it downhill didn't start the bike



Today I stripped the carbs. As suspected above the starting jet passage on the 3 bowls were completely blocked. It took quite a while to clean them up.




After that it started very easily! Except I noticed hesitations around 5k-6k RPM. Decided to look again and sure enough one of the needle sits on top of the plastic stopper, not below! .... silly mistake




After fixing it the bike runs flawlessly! I took it to Frankston for a nice view


Let the good times roll...
gpzninja.blogspot.com.au

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01 Apr 2017 06:39 #758289 by Tyrell Corp
Replied by Tyrell Corp on topic GPz750 R1 (1982) fixing up
Great photos!

Well worth getting your hands dirty on this, you'll love it.

Just been out on mine this morning :)

1980 Gpz550 D1, 1981 GPz550 D1. 1982 GPz750R1. 1983 z1000R R2. all four aces
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02 Apr 2017 00:54 #758319 by HeavenlyMachines
Replied by HeavenlyMachines on topic GPz750 R1 (1982) fixing up
Thanks. Yes it was my first time taking apart 4-inline CV carbs. I was apprehensive first but then everything looks logical and more like 4 times of the same things.

I took it for a fang after work on Friday. There is a verrrrryyy slight hesitation when whacking the throttle open transitioning from 6k-7k rpm on 4th gear. If the throttle is smoothly acted, it is ok.

Would it be because of I set the screw mixture to 2.5 turns instead of 1.5 turns? I set it based on "increasing RPM" method.


Let the good times roll...
gpzninja.blogspot.com.au

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