1981 Kawasaki GPz550 Cafe Build

c4f3 r4c3r

New Member
Well, the bike I'm bringing to the table is a 1981 Kawasaki GPz550. I've previous done a partial restoration of a vintage bike, but this will be my first cafe racer project. They say that this is the bike for which the term "pocket rocket" was coined. We'll see, I have yet to ride it. I bought it about 2 months ago as a non-runner in "rough shape", as the seller put it.

I've been rather busy in the time since I purchased the GPz and have had only limited time to work on it. None-the-less I have already done a few things. So, I will probably send out the first few posts in rapid succession. Not all will be exciting, my intent is simply to document the project as is occurred. I hope you enjoy it.

Cheers,
Todd

PS: Here is a pic of the bike from the Craigslist ad where I first found it.
 

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I live in Seattle, but I found the GPz for sale in the Portland (OR) Craigslist. I was able to negotiate, via email, a sale price of $500 sight unseen, $600 with some spare parts: a spare engine in unknown condition, spare carbs, front fender, gas tank, and wheels. The seller described the bike's condition as "rough" and it was a non-runner. The bike has no kick start (never did, has no facility for one) and had a bad starter clutch. Additionally it was missing the chain. So, there was no good way for me to turn the engine over and get an idea of its condition. Basically I had to decide whether or not I trusted the previous owners assessment of the bikes mechanical condition. I decided that he seemed honest enough, and he hadn't over sold the bikes condition. He was up front that it needed some significant elbow grease.

It took me a borrowed truck (thanks Colton), a rented trailer (Uhaul trailers are a much more reasonably priced proposition as compared to their vehicles, no mileage charge), and an entire day to go to Portland and pic up the bike. But I got it. I couldn't start working on it right away. I had to get rid of an abandoned project first. I had earlier picked up a CL350 that turned out to be too-far-gone and not easily titled that I needed to part and sell before I could start on the GPz.

Here are a couple of pics, one of the bike on the trailer, one of it when I first put it in my garage.
 

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These are GREAT bikes. Top of the 550 heap when they came out and are fairly bullit proof. Good luck and hope it turns out to be well bought!

Matt
 
Thanks Matt! It is definitely going to be a "rat bike" for a while. But I think it is going to make a pretty cool one.

- Todd
 
So the first major job that I decided to tackle was the starter clutch replacement. The previous owner had claimed that he didn't think that this was too big of a job. I've got to say, it is fairly substantial. You've got to take just about every cover off of the engine, the alternator cover, the drive sprocket cover, the clutch cover, the secondary shaft cover, and the oil pan. The exhaust has to come off. The clutch assembly has to be disassembled and removed. The oil pump has to be removed. And the secondary shaft has to be removed. At least that is the procedure for doing it with the engine still in the bike. The procedure described in the Clymer manual involves pulling the motor first.

One of the biggest problems I encountered was removing the clutch hub (regular clutch, not start clutch). Generally this procedure calls for a special Kawasaki tool to hold the hub in place, to keep it from spinning, while you remove the center nut. Well, if you are like me, the ol' McGyver in you comes out and you start thinking about how you can fashion your own. The first thing that I tried was to drill two holes in a long rod and bolt the rod to the towers where the clutch pressure plate spring bolts normally attached. I used that to hold the clutch hub while I put a breaker bar on the hub nut. I promptly busted off two of those towers. Doh! Now I had a new problem. I needed new clutch parts, as well as to replace the starter clutch.

I tried fashioning two other tools, one from a large bar clamp, one from two clutch plates attached to a long bar. Ultimately, neither of these tools worked. I had to buy an electric impact wrench to get that nut off (and apply friction to the hub by wrapping it in rope). I had to scavenge my spare engine for the busted clutch parts.
 

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Need any parts let me know just put a parts bike up for sale since I wanted to go the SR250 and CL360 route. 82 gpz, they look kinda mean when done right and take a few mods and it's the original street fighter. None the less good luck I'll keep an eye on your post to see how much I may regret getting rid of mine.
 
Finally got to the starter clutch, removed it, and replaced it with a new assembly. Here are a few pics:
 

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With the new starter clutch installed and the bike reassembled I finally got a chance to start the bike for the first time. The first press of the start button did nothing (as did the 2nd, 3rd, 4th, 5th, ...). I ended up jumping the solenoid with a screw driver. Like so many electrical problems on old bikes, I would later find out that the only problems was a dirty ground wire (on the solenoid primary side). Anyway, though there was a good bit of valve noise, and a few seconds after I stopped filming this video the bike started dumping green fuel all over the garage floor (from carb overflow tube, probably stuck float from old gas), it did start and run OK. Here is a video of it running, check it out:

http://youtu.be/GXwZoPJV_1k
 
Though there is still a lot of work to do to make this a viable running/driving bike, I couldn't resist the urge to start making some cafe modifications. When I purchased the bike I paid a bit extra to get the previous owner's spare parts. One of these parts was a spare gas tank, from which I intend to build a seat cowl. To be precise, I will use the spare as a gas tank (as it is in better condition than the one currently on the bike, though neither are dent free) and I will use the current tank to make the cowl.

I removed the current tank and pulled of the bits that I would need to transfer over to the other tank (fuel level float, petcock, and cap). I then gave it an internal soap and water bath. I did not assemble the tank that will become the new fuel tank, because it is rusty inside and will need to be cleaned first. But, from the tank I removed, I began to cut the seat cowl.

Below is a picture of the rough cut. Of course there is much more work to be done on it yet, like closing off the end and attaching it to the bike. For now it is just sitting on the bike so that I could snap a photo to give you an idea of what I have in mind.
 

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OK, I got tired of looking at that awful square headlight. And I needed to see what the front end was going to look like once I started dropping things down a bit. Here is a rough mockup that shows the basic changes that I am going for in this first round:

clip on bars
get rid of those mirrors (I plan to add some lane splitters but don't have them yet)
mod the gauge mount to drop them down a bit (smaller gauges isn't in the budget at this point)
mod the ignition key mount to drop it down a bit
shave off the old bar mounting towers
round headlight and new brackets
getting rid of the plastic indicator panel (working on relocating the indicators and fuel gauge)

I will need a different master cylinder. The gigantic one that came with the bike is getting in the way now that I've switched to clip-ons. Anyway, here is a before pic and an "after", sort of (it is only a mock-up at this point).
 

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merc4now said:
Need any parts let me know just put a parts bike up for sale since I wanted to go the SR250 and CL360 route. 82 gpz, they look kinda mean when done right and take a few mods and it's the original street fighter. None the less good luck I'll keep an eye on your post to see how much I may regret getting rid of mine.

Thanks merc4now, I'll drop you a line if I'm looking for any GPz specific parts, to see if you still have any. Good luck on your other projects.
 
Big fan of the 550. Def hauls ass for a little bike. All of the old Kawasaki's have that starter clutch issue. I've replace 3 of them off my kz750 twins, but the twins is much easier than the 4 cylinder. You definitely have to take alot more off the engine with the 4 cylinders to get to the starter clutch. Overall bike doesn't look too bad. Should clean up nicely.
 
Awesome bike... Also a great platform for either a cafe or fighter. I've also got a bunch of Gpz parts laying around. They are mostly 82. Look forward to seeing how your build turns out...
 
I have fond memories of my buddies brand new '81 GPz550 in the living room of his "dome home",and yes there was a cow looking in the front window when he fired it up for us.That bike was amazing.Smooth, fast ,tight and just right.I shit you not.Nice purchase.
 
Thanks guys. It does me good to hear from others who have fond memories and experiences with their own GPzs. Interesting that it doesn't seem to be used that often as a cafe platform. Perhaps because it is from the 80s. But it still has that nice (mostly) straight frame top, tank to tail (at least the '81 does, I'm not sure how the frame is on the later years). I thought the tank was a bit fugly for a while and had plans on changing it out, but it has really grown on me. I'm partial to a tank that drops off quickly at the rear (a blunt rear) as opposed to one that gradually tapers to a point. Anyway, I like the way it is shaping up so far. This isn't going to be one of those immaculate restoration projects. I don't have a huge budget. It will probably always be somewhat of a rat bike. But I want to customize it to the style that I like.
 
Recently had to deal with a good deal of rust in the gas tank that I am planning to use. I decided to use the electrolysis method for a few reasons:

1. I've used it before, so I'm familiar with it and it isn't too difficult (though it does take a while).
2. It doesn't eat away any healthy material from the tank.
3. It is super cheap, provided you already have a power source (which I do, a standard car battery charger).

All told this cost me about $3 and change for a box of washing soda (to make my electrolyte solution) and a few bits I had laying around (the cap from a can of spray paint, a strip of steel I cut from a small sheet I had, and a bungee cord). It worked great, though it took about a week. I had to replace the sacrificial anode (steel strip) about half way through because the first one basically dissolved into mush. I probably should have done this closer to when I was planning on placing the tank into service, to prevent flash re-rusting. But, I've coated the now fairly clean inside with WD-40 and am hoping for the best. Anyway, here are two pics, one of the anode after 24 hours (this is all rust that jumped from the inside of the tank to the anode) and one of the anode with about 4 or 5 inches missing as I found it about half way through the process.
 

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My plan is to get rid of the original plastic console which contained the indicator lights and the fuel gauge. It had 4 indicator lights; right and left turn signal indicators, high beam indicator, and neutral indicator. Well, I am also relocating the handle bars, moving them down, replacing the originals with clip-ons. As such, I no longer have a need for the handlebar mounting towers that originally came off of the top of the triple tree. So I cut them off with the grinder. But when I did so, they were hollow and left some holes behind. While doing a Google search to see what others before me have done with these holes, I found someone who had used them to relocate his/her indicator lights. Sorry, I do not now know where I saw this or I would leave a pointer to person whose idea I borrowed. As luck would have it, I was left with 4 holes and 4 indicators that I needed to move (plus a fuel gauge that I don't yet know what to do with). Below are pics of the original console and of the holes left behind after cutting off the bar towers.
 

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As mentioned in the previous post, I am attempting to fill some holes in my triple tree crown with indicator lights, as seen on another forum post somewhere. Now, the original post didn't say how they had fit lenses into the holes or attached the lights, etc. So I needed to make this part up. I attempted to pour some lenses using a fiberglass resin that someone suggested dried clear. Well, it didn't (distinctly yellow/orange as you'll see in the photo below). I had to grind it back out and re-pour them with a clear-cast epoxy. While they aren't perfect (some artifacts like bubbles), they are much better.
 

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OK, now that I've got lenses in my triple tree crown for my new indicator lights, I need some lights and a backing plate to hold them in place. What follows are several pics of:

1. The backing plate that I made with colored leds in place.
2. Rough wire up.
3. Tidied up wiring.
4. Backing plate attached.
 

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