Tuesday, July 12, 2011

Suzuki GS750 Cafe

Let's start with a cute story.

About a half dozen years ago, I was at the Secretary of State to get a title transferred. It was about three in the afternoon on a Tuesday, and the wait was, as always, ridiculous. I had been waiting for about ten minutes (looking at probably another forty) when one of the clerks announced that they were calling last call on all written tests, and anyone there to take one should come up to the counter.

Seeing a shortcut, I approached the counter and said that I was there to take the motorcycle test, but that I also had to do a title transfer and get a plate. Could I do them all at the same time?

The woman said yes, and gave me a copy of the test.

Even thought I had not read the motorcycle handbook, the test was hilariously easy, took about five minutes, and I passed it easily. So, after being there for less than twenty minutes I walked out with my title, plate, and a motorcycle learners permit.

The next logical step was to buy a motorcycle. That motorcycle ended up being a Suzuki GS500 that I found on Craigslist for about a grand. It was a great bike to learn on, but ultimately not the bike I wanted.

I've always loved the bikes from Mad Max, and wanted something in that style. I ended up buying a 1978 GS750 from a buddy, and after doing some poking around, I decided to go the cafe route.

Here is a crappy cell phone pic of the original bike:


The picture doesn't do it justice. It ran okay, but was far from showroom condition. The first thing I did was replace the handle bars with a set of clubmans, and I removed the tank to pound some knee inserts into it.

Here is the tank with the outline of the inserts marked with tape:


It took some nerve to take that first swing of the hammer. After that, there was no turning back. Here is the tank after the initial pounding, and with body filler to smooth out the surface.

*tip: if you are going to attempt this, put a block or some sort of spacer in the tunnel of the tank. Mine pinched together ever so slightly, but now it is a little tight whenever I have to mount it on the frame.


Here is the tank back on the bike, and the beginning of the first seat pan. I haven't yet chopped the frame:


I really liked the shape of the original "duck tail", so I decided to retain it. I used a couple of ideas I gleaned from other builds to make my tail section. In retrospect, I kind of wished I hadn't. I learned about using fiberglass, so that was cool, but the product I ended up with was big, bulky, not what I wanted, and took a lot of time to make.

Here is the start:


I wrapped the original piece in tape and foil, and then began covering it in fiberglass. It was a messy and imprecise process. I am betting a could do it much better now.

Here is the fiberglass reproduction next to the original. Pretty close, but at no point in time did it occur to me that I was reinventing the wheel. Why make something, when I already have a perfect item sitting right there.

Here is the tail with the beginning of the board sitting on the frame. Also featured is the first crappy paint scheme:


Here is the seat glassed, puttied and sanded, with the beginnings of a seat:


I built it to work on the original hinges. Once again, pointless:


Here it is, mostly assembled:


Kind of ugly, but it is getting there. I traded the original exhaust for a 4-1 kerker style, and also sold the original seat to help fund the project. I should mention that I am doing all the work either in my basement, or my charitable neighbor's garage.

I didn't like the black/yellow, so I repainted it red/silver. Repainting it will be a common theme:


I was having carburetor issues (also common theme), so those had to be fixed, as well as some electrical issues (yet another trend). Here it is torn down and the frame also getting some paint:



Wiring hell (note makeshift soldering station):


I hated the clunky dash, so this is the beginning of a long term streamlining project:


Around this time I also swapped the airbox in favor of pods. I like the look more, and I hated removing that fucking airbox every time I had to work on the carbs. Which was often. This left me with jetting issues that took about a year (and a donor set of carbs) to get right.

I also eliminated the battery, and replaced it with a bank of capacitors. I bought the capacitors off ebay. At the moment, I don't remember their value, or the calculation I used to come up with what I needed. They were wired in parallel, and then wrapped in electrical tape and shoved under the seat. In case you are wondering, the electrical output of the stator fluctuates with engine speed, so this is needed to keep your electrical system steady (otherwise your headlight does some funky stuff, amongst other things). They also help a lot with starting the bike. Which is important, since there is no pushbutton start, it has to be kicked over.

It was around this time that I also bought a second engine from a guy in Cleveland for $80. I needed it to replace my head, as there was a broken exhaust stud that refused to be removed. After trying everything short of EDM (vice grips, WD40, PB Blaster, welding a nut onto the end) I broke a hardened backout bit in it. Sometimes you just need to know when to say fuck it.

As a nice bonus, there was a new Dyna ignition in the engine, which put me about $40 ahead on the deal.

Also during this time I had had it with the wiring harness. There was an almost never ending series of shorts and bad grounds. Since I had eliminated the turn signals and starter, most of the existing harness was vestigial, so I decided to junk it rather than keep fixing it. I designed the new one from scratch, used better wire, soldered almost all connections, and I think I layed it out better for my purposes.

This is a crappy meter that I threw on the ground in a fit of rage:



This is the bike around then (note different paint scheme):


Notice how there is almost nothing in the frame other than motor? I like that.

Unfortunately, now I was sick of my seat. I decided to do something much simpler. The original tail, bolted to a metal pan.




Also, I wrapped the headers. Initially it was just for looks, but it ended up being quite practical. I was chasing down a plug fouling/carb problem, where sometimes cylinders would stop firing. Being able to touch a header to see if it was warm was a great troubleshooting helper. I don't know if any of you have accidentally touched an unwrapped header, but I have. I slipped once while looking at the engine, and reflexively reached out to steady myself. I grabbed a header pipe like it was a monkey bar. It totally sucked, and burned my hand into a clawlike shape for about a week.

I can't stress this enough: Don't do that.

The bike was getting closer to where I wanted it to be. Also, somewhere around this time, the rear wheel bearing ate itself on a ride. In a very rough part of town. Exciting! So, I found another one on ebay. I also repainted the bike again, and stripped some of the aluminum parts (forks, brakes).

Also, the front brakes started to leak (of course), so I replaced the lines with stainless from Z1. I also removed the splitter from the brake setup and ran two lines all the way up to the master cylinder. I can't recommend this upgrade enough, they feel so much better now.




The next summer I broke my collar bone (on a pedal bike) and had a daughter, so nothing of note happened with the bike.

This summer I painted it (again), got rid of the infuriating fuel door, did some more work on the dash, and general cleanup.

Also, my mother made me a leather seat, which I love. It is also the first peace of work done on the bike that wasn't performed by me.










For a 30+ year-old bike, I think it rides pretty great, and pulls strong. To quote a friend, "it's vintage fast", and I'm pretty proud of it.

Here is video proof that it runs:





*other things I forgot to mention:

  • Fork Gators!
  • Lowered the headlight bucket considerably
  • Removed left hand controls
  • LED tail light bulb
  • Louder horn (activated by the old starter button)
  • Since I re-wired it, there are only three wires going into the headlight bucket. Three! Can you believe it?

Not sure what I want to do next. I often think about spoked wheels, but the mags have grown on me. I also think about doing a lighter chain conversion. I like the small gauges JC Whitney sells, but I also like that I have retained and used the stock speedo. Rearsets would be nice, but I don't want anything too "new looking" on the bike. Maybe suspension upgrades. Perhaps I should rebuild that spare engine I have.

If you got to this point by reading the whole thing, thanks! If you just skipped to the end, you have betrayed yourself for what you really are, which is little better than an animal.

3 comments:

  1. What a great job you've done.
    I too am working on the same bike and am greatful for some ideas you gave me.

    thank you
    LOU B'KLYN
    p.S. TELL YOUR MOM WELL DONE!!

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  2. Love what you have done to your GS. I'm trying to help my roommate with his 78 GS750. We are having an issue when you use the left turn signal. The turn signal does not light up or flash, but instead the headlight and brake light flash. I'm thinking bad ground, short circuit, or bad relay. It was working great all summer long then one day it just stops working. Any ideas? Could you email me a copy of the wire diagram that I see in one of your pictures. That would be extremely helpful. Thanks. justin.low@gmail.com

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  3. I may have over looked it but are the brake and throttle cables new and shorter then stock? or did you just rerun them to where the action is smooth?

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