GPz750 R1 (1982) fixing up

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.

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.

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.

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.

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.

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

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.

Looks like you got a good one to bring back. I put the engine of one in a Z650B frame. Enjoy yours.

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...!

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

Great photos!

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

Just been out on mine this morning

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.