1983 Kawasaki GPZ 550

doctorcat

New Member
The story:
In Spring/Summer of 2017, I finished medical school and left my home of Oakland, CA to go become a doctor. Where you end up doing your specialty training is a bit of a lottery, but I ranked and ended up in western New York, near-ish the Canadian border and Toronto.
When we rented our house I noticed an old neglected motorcycle sitting in the back. It apparently ran, but then was put away and not touched. Since being "choppered" it hadn't really been used much.

I'm gonna quote my member introduction here for a moment...

I got the house owner to sell the bike for cheapie, and it was in pretty decent condition all around.
It had been chopped up a bit by a few folks trying to make it less plastic clad. It's not a bad idea, as the frame on these bikes was quite pretty and showing it off is great.

here she is when I first got her, 1983 Kawasaki GPZ550
LHzTMW4l.jpg


now the other side...maybe you can see that brownish gunk on the top of the tank? That was rust eating through from inside the tank to the outside
YqF0UUJl.jpg

I took the tank to a shop to see if they could weld it, but it was far too rusted. There was a hole in the roof and water and snow just dripped away eating the insides and out (gas cap wasn't sealing up right) The shop was interstellar motors, here in ROC, NY. Great bunch of guys!

I looked for another tank, but to be honest I hated the shape of the stock tank. The lines were wrong on the bike. I noticed a member on here JFarhanbod had done up a GPZ550 really nicely (his is an 84) and he fit the 81 style tank on his.

I had to grind off the tabs for my ignition coils and make a bracket to relocate them, but the tank fit great!
DyoKJX8l.jpg

Forgot to mention, the wiring was a mess. Lots of corrosion, lots of stripped wiring that when I drove the bike around at first, it sparked and sputtered. I decided enough was enough, and removed the harness.

I picked up an M-unit and some buttons, plus a domino throttle...

while I wait for those to show up, I started to ponder the seat pan:
I need somewhere to stash a battery, and the electronics.
I also need to mount up a seat somehow, and not the awkwardly shaped stock seat.

I want to have SOME room for storage, so a rear hump is in order (though maybe the battery will eat all that space up.)

Here is the template for the seat I've measured several times and tried a few layups... I had interstellar motors (shameless plug for them again i guess? GREAT shop) weld up the rear frame hoop.
CpB97NGl.jpg


now for the ideas about making an undertray: looks like there isn't much clearance towards the rear of the bike with the tire. I can't follow the triangular plates on the frame where the dual shocks used to mount on the prev year model.
abB7RXGl.jpg
(although I think it would look better this way...)

and then up towards the front, where the factory ignition, and regulator rectifier mounted? Not a bad spot, but totally exposed to the elements.
maybe you can't quite see it, but this is a UNITRAC model suspension and the suspension linkage takes up a lot of that middle area. There's still a teeny bit of space, though. I could probably squeeze an electrics box in there, but I wouldnt fit the M unit I don't think, and I wouldn't want the M unit right next to a boiling hot regulator rectifier.

And then there's the issue of the seat shape: It's going to need to be a taller seat height (a low brat seat makes the bike too small for me)

so I got the idea to build the seat base like earlier, and maybe have that be the electronics tray. Electronics on TOP of the frame rails.
Then somehow build the seat on top of the electronics, and somehow have it swivel or click open so I can take a look at the electronics, and maybe have some storage space in a cafe hump for my gloves when I'm not riding.
aOXgGeCl.jpg


At this point I was frozen in indecision, and pondering how and where to stash the electronics and battery that wasn't sticking right out into the elements. I also didn't want to keep the ratty old foam seat as it didn't have any support.


The bike was then moved to the inside of INTERSTELLAR MOTORS, a well known cafe racer shop here in town (Rochester, NY)
The bike has been moved into interstellar motors shop where I'm continuing to do some more work on it. I got a seat pan layout made of a sheet of steel.
I ran into a problem though. You can see that the tank mount is kind of tough to clear. I have to figure some way to get the seat pan to cover that bit. I have at my disposal a sheet metal bender, but I can't quite get a tiny little right angle as the minimum length between bends is about 2 inches. Somehow I've got to make another mounting point for the seat pan on the factory tank mount, so I think I have to curve the metal around it? Gonna take some creativity, I'm thinking. I'm kinda stuck right now.
khGYi7q.jpg

I cant get around that piece. I ended up cutting off the two side "wings" on the side and just terminating the pan at the tank mounting hump.
SN6JbOM.jpg

underside view of the pan. I still need to somehow attach some mounts to the frame so I can screw it down.
latIArF.jpg



At this point I tore into the carbs and found them completely gummed up with crystals and what can only be described as "GUNK"
cOIkNLz.jpg

more close up of the boogers and barnacles attached to the float bowls, and floats themselves
VbwVfm0.jpg


NEXT:
figured this bit out. now I have to decide if I'm going to hammer the "wings" down on top for a narrowing of the saddle as it approaches the tank. Right now it pokes my legs because it's so sharp.
s3LkkL8.jpg

compare to yesterday
khGYi7q.jpg


so I'm going to rivet the new piece down that I made with the metal bender. that thing is a godsend!

wider shot of the whole seat pan
s3LkkL8.jpg

circles on the green tape are where i'll drill and then place rivets to secure it. I still need to weld cross brackets for securing the seat pan onto the frame.
I6HjzI7.jpg

(gonna hammer the two wide sides down if I can so they dont poke my legs
Actually, I should stop calling it "seat pan" this is just the "undertray"


I'm ordering up a piece of KYDEX Thermoplastic which I will heat form around the metal tray. This will be what the foam and staples for the fabric go onto. I'm going to have a layer of hard foam (like yoga mat material) and then a layer of softer foam on top (maybe even some GEL like from those purple mattresses. I think I have a square of it sitting at home...) I want the seat to have a rounder profile since I've got a narrow arse.

KYDEX is what Gun enthusiasts like to use to make conceal carry holsters. I may be a Californian, but I was raised in Texas and I know a thing or two about firearms! Has anyone here used KYDEX for making a saddle before? It seems to be a good base if it is thick enough?


oh and I'm trying some shapes for a seat hump. I need less space than I thought originally. Going to use a shorai battery. I have two mounting options: 1: use the stock location for a full size shorai, or 2: use the seat hump for a mini shorai.

here's the seat hump design in progress. I may want to make it larger/taller?
A8hX1Uj.jpg


right now it's set up to be a solo seat so it's "in line" with the frame tubing. I could push it back further and allow for a passenger... Gotta have the hump though nowhere else to store the electrics! The monoshock takes up all the room.


okay, first post. let me try and write a proper update here then...
 
So, NEXT:

BUILD THE SEAT:


I got ahold of some KYDEX thermoplastic to try and make a seat pan. Plastic is way easier to staple fabric to, and I got a quote from NewChurchMoto aka Ginger McCabe over in Portland for starting out a seat for me. Here's how I formed the plastic to make the pan. Hammered down the sharp edges on the seat pan (not quite symmetrical, but the metal did kind of what it wanted to do but it works!) I formed it around and down so it "snaps" on then trimmed it back with a dremel. This took like hours and hours of work. Heating the plastic, forming it, then heating another area, forming it, letting it cool and harden, but I'm pretty happy with the result...at least at first...
C92pZig.jpg



laid out the electricals. I've got lots of space back there in the hump.
s80CJAy.jpg


Then a few days later I started mocking up the cowl with cardboard.
You tell ME what's wrong here, I see it and can't unsee it.

RbA13KW.jpg

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so here's what I think: The rear cafe hump doesn't look right. It's either too tall, too round, or both.
Again, I'm stuck, and aesthetically I can't make my mind up. Cut it down shorter? I've obviously got room to make the cowl smaller. It's just a teeny bit taller than the terminal squaring off of the gas tank. It just BOTHERS me. Ideally I wouldnt need a cowl at all and it would be very continuous (I like brat style, but got nowhere to stash the electrics since the 83' suspension takes up the space Id normally use for an electronics box.


WHAT SHOULD I DO, INTERWEBS?

or is it fine and I should just leave it and cardboard looks worse than it will IRL...
 
Another GPZ 550! Nice!
I like the possibilities of these bikes if you dare to do some cutting and welding.

Maybe an idea for the hump:
The upward bends in the frame make a lot of hump designs look out of place. I straightened the rear, to get cleaner lines. And in my opninion, with great succes.
My bike doesn't have a hump yet, but I'm working on it.

I fitted all my electronics under the seat, between the frame tubes. (Even the battery) But yeah, the monoshock design is a pain to work with for that kind of work. But if you pull it off, it looks real nice I think?
 
Good start :)

Like japstar stated, flattening the hump to match the tank profile could work aesthetically and still give it the cafe look and seat comfort will not be affected...win win as they say :)

Just a tip, before you stitch up the undertray/guard get you and a mate to jump the pegs/rear end this will simulate the bike and you hitting a highway undulation at speed with just you on it, then see what the clearance is.

You'd be surprised how much travel you'll need when on the move and it don't look like there is much more than 2" which is tight I reckon. Unless you're a 10 stone weakling haha!

Q: Are the other bikes in the picture yours too?
 
japstar said:
Another GPZ 550! Nice!
I like the possibilities of these bikes if you dare to do some cutting and welding.

Maybe an idea for the hump:
The upward bends in the frame make a lot of hump designs look out of place. I straightened the rear, to get cleaner lines. And in my opninion, with great succes.
My bike doesn't have a hump yet, but I'm working on it.

I fitted all my electronics under the seat, between the frame tubes. (Even the battery) But yeah, the monoshock design is a pain to work with for that kind of work. But if you pull it off, it looks real nice I think?


Omg! Japstar! Your bike and JFarhan on here were my inspirations.

Funny I just checked your build thread. The bike right behind mine IS Interstellar's Suzuki GS!!!! Andy Jody and Rich are awesome and helping me out on this. Just seeing how they did stuff on their bikes has inspired the heck out of me too!

I LOVE YOUR GPZ!!!!

I'm gonna be putting lotsa work into it this weekend

Vapor blasting the carbs: as y'all say carbs should be raw alloy!
Stripping Black paint off the tank.
Welding or drilling bracket for the ignition coils.
License plate bracket with lights.
Hopefully wiring the handlebar controls. Plan is for face front end swap over winter. Parts here get cheap once the snow falls!

I wanted to swap the swingarm for a zephyr unit and 17" rear wheel but I'll leave that for next year. Going back to dual shock possibly...
 
bad day today. tried and tried to free the rear brake pivot. it's very seized and a hammer and torch have no effect. neither does 2 days of PB Blaster penetrating oil.

going to have to drill it out, but it ate my titanium drill bit.

what next? Cobalt? Tungsten? anyone have an amazon link? Seriously. I'm out of ideas and this damn thing is STUCK. I have a new one coming but WOW this is bad.
22049791_984320127768_698703648860767637_n.jpg


stuck for now. no progress. was hoping to ride it before the snow hits, but it looks like a fantasy.

on another note, though, I vapor blasted the carbs and cleaned them up REALLY nice. Jet kit on its way!
 
doctorcat said:
Omg! Japstar! Your bike and JFarhan on here were my inspirations.

Funny I just checked your build thread. The bike right behind mine IS Interstellar's Suzuki GS!!!! Andy Jody and Rich are awesome and helping me out on this. Just seeing how they did stuff on their bikes has inspired the heck out of me too!

I LOVE YOUR GPZ!!!!

I'm gonna be putting lotsa work into it this weekend

Vapor blasting the carbs: as y'all say carbs should be raw alloy!
Stripping Black paint off the tank.
Welding or drilling bracket for the ignition coils.
License plate bracket with lights.
Hopefully wiring the handlebar controls. Plan is for face front end swap over winter. Parts here get cheap once the snow falls!

I wanted to swap the swingarm for a zephyr unit and 17" rear wheel but I'll leave that for next year. Going back to dual shock possibly...
Haha, thanks :p
I'm also still planning to do a front end swap for a '99 R6 front fork. I should be able to get verything for under 150 euros. But as I bought a KTM 640 Adventure a few weeks ago, and I'm rebuilding an apartemenet, the budget is a bit limited for the moment. Just have to post some updates for the bike. Engine is mounted back together and she got her first circuit day. Still some adjusting of the valves and carbs to do.
doctorcat said:
bad day today. tried and tried to free the rear brake pivot. it's very seized and a hammer and torch have no effect. neither does 2 days of PB Blaster penetrating oil.

going to have to drill it out, but it ate my titanium drill bit.

what next? Cobalt? Tungsten? anyone have an amazon link? Seriously. I'm out of ideas and this damn thing is STUCK. I have a new one coming but WOW this is bad.
22049791_984320127768_698703648860767637_n.jpg


stuck for now. no progress. was hoping to ride it before the snow hits, but it looks like a fantasy.

on another note, though, I vapor blasted the carbs and cleaned them up REALLY nice. Jet kit on its way!
You're lucky you have the TK carbs, they supply jet kits for those. My Keihins are unknown as it seems. They only fitted the gpz's with them for two years or something.

Concenrning the brake pivot point:
Can't you make another one on the lathe (or ask a friend)?
Than cut out the old one, and wild the new one in place.
I'm afraid if you will keep messing around with drill, the part will be too damaged anyway to still reuse it.
 
GOT IT.
lil' @#$^%er. (insert your own expletives. I made up my own curse words as I was hitting it. I think the guys at interstellar may have thought I was having a stroke.)

PB Blaster helped a lot...
ZnuRlYC.jpg


tools of the trade: a tapered hammer with a flat end held against the drilled pivot point to keep it centered
a big hammer named "the persuader"
lots of lube (hehe...)

iTCKnFQ.jpg



now: WHERE THE HELL DO I MOUNT MY IGNITION COILS.

the stock coils are HYOOJ. they don't fit under the new tank without rubbing. I wanna put them underneath the frame, but I'm gonna have to make and bend brackets from steel and drill into the frame. I think I'm going to put them here (pic)

7iFzvFd.jpg


what do y'all think?
anywhere else I could stash the coils that you think would be better? was gonna ground them to the frame right there too...


lastly, a friend wanted a ride on the bike. Sitting my butt down on the seat against the tank, I don't think another generous serving of booty with fit on there. =(

is there ANYWHERE ELSE I could stash the battery on this thing? The monoshock linkage makes it a pain in the rectus to fit any kind of battery tray down there...
 
brackets have been made! Gonna take some photos this evening of the progress. I may redo the seat pan, I have plenty of plastic left. I wanna make space for a passenger if need be... but cover it with the cowl most of the time.

hard to figure out how to get the battery on there and have someone safely sit ON TOP of the damn thing.


OH! OH! ALSO! just discovered a ninja 650 rear shock fits (but it's a lot shorter) gonna try and get a used VERSYS rear shock because it's a bit longer and I don't have to custom fab a new dogbone to raise the bike up.

Maybe I don't have to buy an expensive ass rear shock and can use a modern sportbike shock. the CBR959 shock also fits and has significantly less travel which is actually what' im going for (this is a road bike for weekend track days and cruising around town with the local vintage club)
 
doctorcat said:
brackets have been made! Gonna take some photos this evening of the progress. I may redo the seat pan, I have plenty of plastic left. I wanna make space for a passenger if need be... but cover it with the cowl most of the time.

hard to figure out how to get the battery on there and have someone safely sit ON TOP of the damn thing.


OH! OH! ALSO! just discovered a ninja 650 rear shock fits (but it's a lot shorter) gonna try and get a used VERSYS rear shock because it's a bit longer and I don't have to custom fab a new dogbone to raise the bike up.

Maybe I don't have to buy an expensive ass rear shock and can use a modern sportbike shock. the CBR959 shock also fits and has significantly less travel which is actually what' im going for (this is a road bike for weekend track days and cruising around town with the local vintage club)
Why do you want a new rear shock?
 
the factory one has not one but TWO coil "helpers" to keep it from collapsing on itself. It's basically not a shock at all, it's just a rock hard spring.
The forks look like they can be rebuilt, but the stock shock never was meant to be re-buildable. I could have it gutted and revalved, but a new one from YSS custom built to specs is just as expensive.

Haven't done a lot of work on the bike in a couple weeks. Been busy with 80hr weeks at work and only 1 day off out of every 7 I use to sleep. Sleep is the only thing that gives me pleasure right now :-x

Here's what I did last:
Mockup of the bike, with the headlight shell, so I can get a sense of what "complete" looks like at this stage.
YUQED3e.jpg


deciding to make the seat longer. I'd like the option of a passenger, even if it's a ride around the block. hiding the battery and electronics just got a lot harder. I *DID* grind the tabs off from the old factory stuff so I can make something new on my own.
esrdwwT.jpg


The view out of the window... KODAK city!
Xl5cfaK.jpg


happy winter, y'all. We just got our first snow, but it didn't stick. Bikes are put away, and I'll be putting around on the ruckus when it's not icy.
 
What's a coil helper?

And you can open u the stock shock, clean it and put new oil.
It's designed voor de bike's stock weight. If you trash some parts and lower the weight, the shock is already very good.

And I like the color of the bike altogether :)
 
well, I went to check out a wrecked GSXR today, but the front end had a broken front fork: it was dented in a place that means one tube would need replacing.

The stock forks are out and need a complete overhaul. The electronics are mocked up and ready to be mounted. The wiring needs to be done. The snow is out in full force here, so it's time to head back into the studio/shop and make things happen again. I'm just having a really hard time finding a complete front end for the swap...
 
doctorcat said:
well, I went to check out a wrecked GSXR today, but the front end had a broken front fork: it was dented in a place that means one tube would need replacing.

The stock forks are out and need a complete overhaul. The electronics are mocked up and ready to be mounted. The wiring needs to be done. The snow is out in full force here, so it's time to head back into the studio/shop and make things happen again. I'm just having a really hard time finding a complete front end for the swap...

I have a gt550

Same bike at the gpz but shaft driven and dispatch no fairing... ( forks also)

If you do put gsxr forks on there please please let me know how you get on... forks are different than the gt550 but everything same sizing.



Sent from my iPhone using DO THE TON
 
did a little more work with a free afternoon.
Removed the rear swingarm and factory shock. It had "spring helpers" wedged in there (it was definitely blown) so it was a pain to remove. Currently awaiting a new adjustable rear shock and powdercoating the swingarm silver to make it sort of match with the Z1 and the ZRX styling

co0XQqam.jpg

r4bMthVm.jpg


going to get the tank painted but I can't decide on a color.
Stay white like the original? I'd add gold glitter metallic in there
definitely NO RED.
do Kawi green?
something ridiculous like purple sparkle/raspberry café?
 
doctorcat said:
did a little more work with a free afternoon.
Removed the rear swingarm and factory shock. It had "spring helpers" wedged in there (it was definitely blown) so it was a pain to remove. Currently awaiting a new adjustable rear shock and powdercoating the swingarm silver to make it sort of match with the Z1 and the ZRX styling

co0XQqam.jpg

r4bMthVm.jpg


going to get the tank painted but I can't decide on a color.
Stay white like the original? I'd add gold glitter metallic in there
definitely NO RED.
do Kawi green?
something ridiculous like purple sparkle/raspberry café?

Z1 and ZRX styling for the win.
 
another update:

YSS fork cartridge emulators have been installed. It wasn't hard at all; everyone should do this to their damper rod fork! No need to suffer shite suspension!
Progressive spring kit installed.

I have to delete the air assist somehow because that's useless to me now...

YSS rear shock ordered with appropriate spring.

And then I started on the wiring harness. I've got the grounds to the frame sorted out, the M UNIT is installed onto the seat pan, and the battery is tentatively mounted back a little further than before. IT'S HAPPENING. THIS THING WILL RIDE.

Pretty soon it will be an exercise in styling the bike to my liking which is a lot less headache I think.
 
I just got the Regulator/Rectifier mount made, and the connectors put together.. I've got the whole electrical system for accessories working. Now I just need the starting circuit finished.

Here's how I ended up mounting the M-Unit and the battery at the back. I opted for a Shorai since I plan on really riding this bike and I didn't want just a little ballistic battery alone to rely on.
K2ubauw.jpg


New rear shock from YSS suspension setup for my weight.
6bAdAUA.jpg


rear wheel back on, new shock mounted
0oABtRE.jpg


new front end: This will have to wait to go on. It's a ZX10R front end from 04. Can't find conversion bearings that will fit it...
0cGSCnn.jpg



annnnnd closing up the shop at night
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between saving lives and working 80hrs a week most weeks, things have been slow but steady. Hours should be better in about 6 weeks.
 
I feel like you might already know this, but if there isn't a conversion bearing option you might be able to go the route of pressing the gpz steering stem in zx10r lower triple tree. My kz750r1 is using a zx9r upper and lower yokes with a kz steering stem. If the zx10r steering stem is smaller than the gpz stem, you're in business. Vice versa with those dimensions would make things a little trickier.
 
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