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Author Topic: 1981 Kawasaki GPz550 Cafe Build  (Read 27346 times)

Offline c4f3 r4c3r

  • Posts: 44
Re: 1981 Kawasaki GPz550 Cafe Build
« Reply #40 on: Jul 13, 2013, 16:27:00 »
My original plan was to use the bottom of the old seat foam, as it already had all of the contours of the seat pan, but sliced down and with new foam added to the top. I tried this. But the old foam was in sad shape. So I just used the new foam. I didn't cut every contour into it, but I cut out the biggest ones so the it fit fairly nicely. I tried a few tools, the grinder seemed to work best.

I taped the edges of the glass backing to make sure that they wouldn't wear through the fabric. The fabric I chose was marine vinyl. I used spray adhesive to hold things in place temporarily, stretched the fabric over the foam and around the glass backer, and attached it with pop rivets.

I intend to make another one for the seat back, but haven't gotten to it yet. Here are a few pics of the process and results:
1981 Kawasaki GPz550 Cafe Project - http://www.dotheton.com/forum/index.php?topic=47139.0
1971 Honda SL350 original - http://sl350.blogspot.com/

Offline c4f3 r4c3r

  • Posts: 44
Re: 1981 Kawasaki GPz550 Cafe Build
« Reply #41 on: Jul 15, 2013, 15:12:32 »
I've finished the rebuild of my custom triple tree crown, with the poured lenses for the relocated indicator lights. If you read my earlier entry you'll know that I built this once before, but at the very last moment of installation (setting the torque on the steerer clamp bolt) a chunk snapped off. For no apparent reason. Anyway, I've started from scratch and recreated it. This one isn't quite as nice as the first, I rushed it a bit. But hey, it is done, installed, and torqued. Here is a pic:
1981 Kawasaki GPz550 Cafe Project - http://www.dotheton.com/forum/index.php?topic=47139.0
1971 Honda SL350 original - http://sl350.blogspot.com/

Offline c4f3 r4c3r

  • Posts: 44
Re: 1981 Kawasaki GPz550 Cafe Build
« Reply #42 on: Jul 15, 2013, 15:18:54 »
Actually got the bike out of the garage yesterday and took it for a ride. At first it wouldn't shift out of first gear. I was convinced that it had something to do with Kawasaki's "positive neutral finder", a device that doesn't allow you to shift from first to second unless the bike is moving. I was online trying to figure out how this system worked and how it could fail. I was afraid I was going to have to tear into the gearbox again. But then I found the culprit. When I installed the rearset, the part the mounts on the actual gear shift was a tooth off in position. This lead to the shifter being a bit off in angle. Which in turn meant that it was hitting the engine case. So, it wasn't shifting because the shifter was bumping into the engine keeping it from moving far enough. Ha ha! I should have spotted it sooner, but I'm glad that was the problem. The fix was simple and I got to ride around a bit. Here is a pic of the bike outside (the stain on the ground is gas, it dumped some gas out of the carb overflow tubes on multiple carbs - more work to do):
1981 Kawasaki GPz550 Cafe Project - http://www.dotheton.com/forum/index.php?topic=47139.0
1971 Honda SL350 original - http://sl350.blogspot.com/

Offline Maritime

  • DTT SUPPORTER
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  • Posts: 9234
Re: 1981 Kawasaki GPz550 Cafe Build
« Reply #43 on: Jul 15, 2013, 15:58:20 »
Nice, first rides are always full of adrenaline and fun.
The GL Rebirth: http://www.dotheton.com/forum/index.php?topic=68337.0
CX500 Low budget Bobber : http://www.dotheton.com/forum/index.php?topic=43617.0
"Beer makes you feel the way you ought to feel without beer" -Henry Lawson
"Beer is proof that God loves us and wants us to be happy." - Thomas Jefferson

Offline c4f3 r4c3r

  • Posts: 44
Re: 1981 Kawasaki GPz550 Cafe Build
« Reply #44 on: Jul 15, 2013, 18:16:15 »
Nice, first rides are always full of adrenaline and fun.

Indeed. Especially when I've assembled the bike, you never know what might pop off. ;)

The tires won't hold air for long, the forks are leaking considerable oil, the nose dives pretty drastically under hard braking, the rear brake bleeder valve is leaking, the carbs are dumping fuel out of their overflow tubes, ... But for a moment none of that matters. I'm riding the thing instead of wrenching on it. And it is a thing of beauty.
« Last Edit: Jul 15, 2013, 18:20:37 by c4f3 r4c3r »
1981 Kawasaki GPz550 Cafe Project - http://www.dotheton.com/forum/index.php?topic=47139.0
1971 Honda SL350 original - http://sl350.blogspot.com/

Offline c4f3 r4c3r

  • Posts: 44
Re: 1981 Kawasaki GPz550 Cafe Build
« Reply #45 on: Jul 23, 2013, 14:31:20 »
Took the bike to Backfire Motorcycle Night last week, a monthly gathering here in Seattle for cafe/rat/vintage bikes. The bike still has a whole host of issues to be dealt with. But I couldn't wait. We made it there fine, and had a good time. But, on the way back ...

I was riding home after dark. I was in the left lane of two north bound lanes (35mph city street, not a highway or anything). Home was perhaps two or three miles away. Everything was going along fine, as it always is, before it isn't. All of the sudden, out of the blue, my headlight falls off. Ha ha. Right out of the bucket, the bulb and trim ring. Now, it doesn't fall all of the way to the ground, fortunately. Instead it falls down and lands on my front fender. It is sort of perched there, precariously, and hanging by some wires. I quickly check traffic in the lane to my right and extricate myself from the road. The fasteners are gone, apparently they have vibrated loose. Fortunately I had the foresight to pack a bit of duct tape and some bailing wire. I was able to cobble it together and ride home. I've subsequently added a bit of thread locker to the replacement screws.

Here is a pic from right before I set out that day:
1981 Kawasaki GPz550 Cafe Project - http://www.dotheton.com/forum/index.php?topic=47139.0
1971 Honda SL350 original - http://sl350.blogspot.com/

Offline caferay

  • Posts: 159
Re: 1981 Kawasaki GPz550 Cafe Build
« Reply #46 on: Jul 23, 2013, 16:34:56 »
I thrashed a gold '83 GPz550 for ten years and close to 100,000 miles. That was a quality bike. Even the clutch lasted the whole time.

I like what you did here, but I would have taken a mould off the tank and done the tail in glass, and the large rear surface area is begging for a round light, or twin round lights,  not under the tail.

The air forks were really crap on this bike, the only thing wrong with it, get a  set of progressive springs.

Offline c4f3 r4c3r

  • Posts: 44
Re: 1981 Kawasaki GPz550 Cafe Build
« Reply #47 on: Jul 23, 2013, 20:08:54 »
I thrashed a gold '83 GPz550 for ten years and close to 100,000 miles. That was a quality bike. Even the clutch lasted the whole time.

I like what you did here, but I would have taken a mould off the tank and done the tail in glass, and the large rear surface area is begging for a round light, or twin round lights,  not under the tail.

The air forks were really crap on this bike, the only thing wrong with it, get a  set of progressive springs.

I considered taking a mold off of the tank and doing it in glass. But the bike came with a spare tank. And it isn't that heavy (fairly thin walled). Also, I'm learning as I go. So working with metal (i.e. welding, forming, etc.) has been a valuable part of the process. I did use some glass in the seat (for the upholstery base).

I sort of agree about the tail light, but didn't really see it until after I'd installed the other light. I went for under the tail because the entire tail section is hinged (eventually I intend to tuck the electronics up under there). I wanted everything that was wired to be attached to the non-moving bits (so I didn't have to worry about pinching wires and such). But I may change it up at some point.

Regarding the forks, could you elaborate on the fork modification you recommend? Did you do away with air? I am about to tear into my forks in the near future, to replace leaky oil seals. That would be a good time to consider any other potential changes.
1981 Kawasaki GPz550 Cafe Project - http://www.dotheton.com/forum/index.php?topic=47139.0
1971 Honda SL350 original - http://sl350.blogspot.com/

Offline caferay

  • Posts: 159
Re: 1981 Kawasaki GPz550 Cafe Build
« Reply #48 on: Jul 24, 2013, 11:44:57 »
The forks had air adjustable pre-load in 1983, not sure about '81 -do the fork caps have shraeder valves? I don't see the air cross-over tube, so I think you have conventional forks. My '83 was a mono-shock rear. That was the big change between 81 and later years.

Regardless, the forks were under sprung and under damped. All this involves is replacing the stock springs with some stiffer ones that have a progressive spring rate (not just stiffer springs or longer springs!). Easy, especially if you are doing the seals anyway. This will avoid bottoming out under braking. Increase the viscosity of the fork oil for stiffer dampening. This was really common to do back then, as the Japanese factories tended to set up smaller bikes for 150-160lb riders.

The fender was steel on these bikes in all years, and this is because it also acts as a fork brace, so don't remove it, and consider even adding a fork brace. I'd put gaiters on as well. These became uncool in the 80s, but they served a good purpose. A mechanic i knew noted that changing fork seals escalated his shop in the 80s because the open stanchions were getting nicked by rocks and seals were getting shredded.

Thread lock may work, but loctite blue with polymer lock nuts will hold forever. You may need a rubber washer if there is high frequency vibration.
This bike is looking cool. You should keep the original red and those stripes. This was an iconic bike.
« Last Edit: Jul 24, 2013, 11:50:03 by caferay »

Offline goochwarmer

  • Posts: 111
Re: 1981 Kawasaki GPz550 Cafe Build
« Reply #49 on: Jul 24, 2013, 13:49:07 »
The beauty of getting on the road!! Even with all the problems that linger you got a hell of a bike. I've been out on my KZ almost every day this month, every night I'm tweaking or wrenching something else. I've thought of redoing the springs on mine like CarfRay talked about and was thinking of changing out the entire front end....then my wallet yells at me again. Great looking bike!!
Yesterday I ran into an old girlfriend and I thought I missed her.....................so I backed up and hit her again. Ya know, sometimes I really do miss her.