Back From The Dead

There is something deeply satisfying about bringing old and long dormant machinery “back to life.” It is a tribute to civilization and engineering that it is possible to do so. That a precision machine can sit and quietly rust and deteriorate for decades, and then be brought back to working condition, particularly without major reconstruction, is for me and many other people, a source of calm enjoyment in and of itself, independent of the actual utility of the item.

It was not always so. My first foray into this process was necessitated by my purchase of the Siata...a partly restored “rolling chassis and body” accompanied by nine boxes of parts.

I did not want to build the car...I wanted to race it. But the process, described elsewhere in this blog, 

 required me to develop a “Zen state” of mental quietness in order to “get there.' No frustration and no rushing was going to make my goal quicker or easier to reach.

This first step to actual enjoyment and appreciation of the process of restoration led to a number of other projects with varying levels of effort and quality. I developed decent skills in the repair and refreshment of mechanical systems, as well as recognition of my own limitations, and appreciation for the work of others who could perform tasks I could not do acceptably myself..like body and paint, machining, or “serious” engine work.

The above is the overture to my latest “opera¹”...dragging my Suzuki GS750 back from oblivion. As hinted at the end of “Ashes in the Handlebars,” written in the summer of 2018, I was toying with the idea of resuscitating this derelict; for reasons I could not justify. The article described its rather sad and neglected state at that time, after spending many years in a leaking outdoor “shed.”

I have few pictures of the bike before I started working. Here are the only two I could find. 

Masked for Painting
But Deteriorated painted case in view

Original and pitted front fender

 When the clear coat on the cases deteriorated I painted them black but did a bad job...this was still pretty early in my learning curve. The second photo shows how badly much of the chrome had pitted.

I knew for certain that I no longer have the energy or the interest in doing a complete rebuild of a go kart, no less anything more complex. I was simply not going to pull the engine/transmission assembly out of the bike. If I could not get it to run, and run well, I was going to abandon the project and simply buy a smaller bike such as a Suzuki X6 (see “Ashes in the Handlebars,” 7/14/18) . Even if I could get the GS running I was not convinced that it was manageable given my aging bones and deteriorating strength. 

The X6 weighs about 300 pounds...the GS tips the scale at over 500. I always gravitated towards two strokes for that very reason. I never weighed more than about 150 and a two stroke had plenty of performance while being well within my ability to fling around or get up on the center stand. After 40 some odd years away from the GS and at my current 135 pounds I was shocked at how difficult it was to do that, in order to begin evaluating what it might take to get it on the road again.

“Job 1” (as Ford used to say) was to learn “is the motor frozen?” This was easy to test, just gingerly pushing on the kick starter. There had been no oil circulating on the cylinder walls to lubricate them for something like 35 years, so “gingerly” was the watch word...I did not want to just jump on it and risk scoring the cylinder walls or breaking rings.

It was a bit odd but a good thing that Suzuki still had a kick starter on a bike in 1977. My Yamaha 305 had electric start in 1965, as did my 66 X6, so it is interesting that 12 years later the Japanese bike manufacturers still had this “belt and suspenders” setup. It sure made it easier to confirm that things were still movable inside the cases after all those decades.

It would have been easy to leap from that success to try starting the bike, and it would have been a mistake. That long, out of circulation oil had been sitting in the crankcase for decades. It was obviously long past its prime. And, who knew the status of valve clearances, or whether valve springs might be about to snap? It was also wise to manually squirt oil onto the cams to pre-lube the upper end. While I was at it I drained the oil and pulled out the oil filter, which was clean with no sign of metal in it or the drained oil. The upper end also looked decent, so with the purchase of a set of cam lifter pucks, a case of oil, a cam gasket, and a new oil filter, I had completed the second round of verification steps. 

I was concerned about parts availability for a 40 year old machine. Fortunately there were a lot more GS bikes built than Siata cars, and it was not 1983 with no internet to allow easy research of such questions. I could not anticipate everything I might need but was encouraged by how much seemed to be available, and from multiple suppliers. Of course just because they listed the parts did not mean they actually had or could get them, but at least it seemed there was not a lot of obvious “unobtanium” or “cantgettem” parts.

I was anxious to see if the bike would start and run, but wanted to be smart, though that meant being patient. “Smart” said first see if it would crank and then make sure cranking it would generate the needed oil pressure...understanding that neither of these had happened for more than three decades.

The GS does not have an oil pressure gauge, but it does have a low pressure warning light...one big enough to read by! While it might be possible to use the kick starter to generate oil pressure that would indeed be a tedious process so I was hopeful the electric unit was working. 

I removed the old (and likely original) battery and connected a remote utility battery. I squirted some WD40 into the ignition switch and wiggled the key and sprayed and wiggled and sprayed and gradually it woke up and once turned showed me lights, turn signals, and the horn, but no “grr, grr, grr” from the starter, though with the instrument panel working I could use the gear indicator to verify that I could get the transmission into all five gears plus neutral.

It is virtually impossible to remove the cover over the starter with the carbs in place, so I was hoping the issue was something in the switch. After opening it up and looking at a bunch of tiny parts I thought it would be best to try and just replace the whole thing...it also contains the kill switch and the “Hi/Lo” headlight switch. Suzuki did a great job of using “plug and socket” connectors all over the wiring so sub-assemblies are fairly easy to replace, but I could not find a new OEM unit or a used one which had the correct round starter button. Using the wiring diagram from my Clymer repair guide I wired around the original circuit with a pushbutton in a bracket I fabricated, temporarily hose-clamped to the right handlebar.

It worked perfectly and, with the plugs removed, the bike cranked happily and after a few seconds the freshly changed oil put out the low pressure warning light. A really good sign that things might be healthy inside the engine cases. 

I was not out to “restore” the GS. While I cleaned up and touched up many deteriorated areas on the frame and handlebars, and power wire brushed any bolts taken out for the maintenance I did to get the bike into running shape, I was not trying to make it “look like new.” What I was after was an acceptable looking result which ran and handled as it should. But of course any items I had to remove to repair got cleaned up and painted before I put them back on. And I tried to use paint which made them look as close as possible to the way they did new. So, for example, when I removed and refurbished the cabs they got painted with a spray which closely duplicated the cadmium plating of the machinery.

Much of the work was straightforward. Unlike a car, a motorcycle's raw mechanical bits are all more or less out in the open and, in theory at least, are easily accessible. The theory does break down for some items though. The very nature of the bike's compactness means there is a lot of “stuff” which has to be packed into a very small footprint. That can mean either removing a lot of other “stuff” in the way of what I needed to get to, or trying to figure out how to remove nuts or bolts which the factory made special tools to access which I did not have and could not get.

On the other hand, a really attractive bike like the GS is impressive visually in no small part due to the engineers and designers ability to make all that raw mechanism somehow look good.

There were, however, a few mechanical challenges that were real head scratchers to diagnose, and then were also frustrating due to long timeframes for the search and securing of the required parts for the repair. Solving these issues gave me some of the deepest satisfaction of the project.

Front master, rear caliper, rear master, rear bearings...tires

The full list of items I worked on in bringing the bike back mechanically and cosmetically is extensive. For anyone interested it is printed at the end of this post. Underlined items are those which are still to be executed or completed. 

For this article I will concentrate on those things which were the most challenging and which, therefore, brought the greatest satisfaction to me in resolving. The first of these, mentioned at the beginning of the post, was diagnosing the failed starter button and wiring around the stock item successfully. The next one I tackled was the front brakes.

The front caliper is a single, floating piston design. Hydraulic pressure causes the entire assembly to slide on its mounting bolts, when the piston pushes the “active” pad against the rotor, thus pushing the entire assembly, from the “passive” pad side, tightly against the other side of the rotor. I tested this movement using air pressure with the caliper removed from the bike. The piston moved freely and the seals did not appear to be deteriorated in any visible way so I was fairly confident in just replacing the pads and putting the assembly back on the bike. But then a stumbling block arose in regard to the front master cylinder. 

Suzuki very quickly abandoned the single front disc and moved to a dual disc setup which still used the same floating caliper design. According to all the material I could find this occurred almost as soon as the bike was revealed to the public, which happened in October of 1976. So it may well be that only the initial run of GS750s, produced prior to that date, got the single disc setup. As shown in the photo, 

Talk about an early version
Built the month before the public presentation

 this would include my bike, produced a month before that public unveiling.

Though the caliper was OK the brake lines to it were not...and since Suzuki used lines with swaged on banjos there was nothing I had which could be poked into the lines to clear the clog. So I got new lines...and then found that the handlebar master was not working. 

Though the historic material I have found on the internet has been quite useful, none of it has totally clarified the model designations for the 750. For 1977 the OEM parts lists for the bike had a “GS750” and “GS750B” selection in their menus...but the diagrams for various assemblies and the parts listed were identical...and were for a single front disc, floating caliper, spoked wheel bike. Yet at some pint the “GS750” selection was removed from these menus.

My bike's serial number plate
First time I looked at it was as I started the refresh project
Note the lack of letter designation after the pre-printed "GS750"
Is this a "pre B?" An "A" Version?

I ordered a rebuild kit for the “GS750B” but the piston and seal were smaller than the old ones I removed from the master. My own belief is that the available kit is for the dual disc version. If I remember my physics correctly the smaller diameter would create more pressure, which would be needed to activate two, rather than one, pistons. At any rate the rebuild kit was useless.

The old components, once cleaned up, looked ok, but when I reassembled the cylinder with them it leaked upon application of pressure, so could not be used. I will keep it on the shelf, hoping I might later find some non-Suzuki components which might work. Meantime I bought an aftermarket cylinder. To make it look like it “belonged” I used a heat gun on shrink tubing to create a black end of the activation grip handle to sort of match the factory look on the clutch lever. Of course I also had to modify the original wiring to connect to the new rear brake switch. But once installed and road tested I was satisfied that I had solved the front brake problems. So on to the rear.

Unlike the front, the rear caliper was a mess...totally frozen. This end of things used dual pistons on a single disc, with its own master cylinder, tucked up inside the frame. I knew things were going nowhere until I had a functioning rear brake and that meant first of all a functioning caliper. 

In fact, the road test I did of the front brakes were after I resolved much of the rear brake issue. But getting a working caliper was only the first step.

Although aftermarket and OEM pistons and seals were available for the unit, I could not get the old pistons unstuck so this did nothing for me. I finally decided that, though expensive, the best approach was to put the old caliper on the shelf and fiddle with it later, and bought a new OEM replacement out of Japan, complete with pistons.

Also, unlike the front, the rear lines from the master joined to a rigid tube in the middle, and then from this tube there was a flex line to the caliper. Though one end of these flex lines used the same swaged banjos as in the front system, the straight connector at the tube, and the straight tube itselg, meant I could both poke a wire down each segment and also use a spray tube on an aerosol can of Brakekleen to flush out these lines. Once cleaned and examined I could spray again to test that they were clear and then reuse them, preserving the original look and function.

Problem was, after rebuilding the rear cylinder, the brakes had a tremendous amount of drag, and I did not know where it was coming from. I did not see how the lines could cause this, so in my evaluation it had to be either the master or the caliper itself was not releasing when I released the brake pedal. It did not take me long to devise a way to isolate the issue to one or the other.

I first test road the bike and stopped it using only the front brake, as described above. That worked fine, though of course the rate of deceleration was painfully (and potentially dangerously) slow. I then connected lines from the front cylinder to the rear caliper, and did a ride using only the rear brake. That worked fine and there was no residual drag on the rear when I released the brake pedal. But just to be sure I had isolated the problem to the rear master I did one more test. I connected the rear master to the front brakes...and the drag problem moved from the rear to the front, proving that, simple as it is, something in the rear master was bad. 

Though relatively simple the business end of the master is difficult to clean out as it narrows down from the general internal diameter of the cylinder. The integral reservoir, used only, I believe, on these “pre B' or “A” models, does not exactly help as it makes it clumsy to work with just the cylinder part of the unit.

This cylinder seems to be irreplaceable, as Suzuki quickly went to a no doubt less expenive and more generalized remote reservoir system. So I purchased a complete new unit, fabricated a mounting system for the reseroir, installed it, and re-tested the brakes with total success. Major problem solved but at significant expense and time to deliver two major parts from Japan.

Though the brakes now worked well there was still something in the rear end causing me mental discomfort in my testing. The 40 year old tires were not confidence builders, but there was a binding when I rotated the wheel manually and a howling while riding I did not like. And finally, I decided to test side play in the wheel and found about an eighth of an inch of it which appeared to be in the hub, though at first I misdiagnosed it as in the swing arm, which supports the rear suspension and wheel...sp I now have new needle bearings and seals for that unit, if I ever need them.

I thought the binding might be one or more frozen chain links. The bike had over 40,000 miles on this original item, so I decided to replace it and, since this requires dropping the swing arm, I would look at that assembly as well as the entire hub unit at the same time.

Once I had the wheel off the binding problem became obvious. 

Pretty Obvious Issuer
Where is the cage that retains the balls?
For that matter, where are the rest of the balls?

 But exactly how and when did that cage break? Where did the remaining balls go? The only time the rear wheel was off the bike was to replace a worn out rear tire, and that was done by the dealer where I bought the GS. And with the hub on the wheel and the wheel on the bike there is simply no place for balls to escape the hub even if the cage broke. 

Selby Motors is long gone from Redwood City. But if they were still around, after finding this issue and knowing no other place where this failure could have been noticed and corrected before it wound up potentially killing me, I would never bring the bike back to them. Incompetence in repairing dangerous machinery used by others is just unacceptable...and I see no other answer which could explain what I found.

At any rate, I ordered a new bearing set and seal and installed them..the new bearings are sealed and require no internal lubrication. Once I reassembled everything and did another road test the bike was back to being the predictable and docile though powerful ride I knew and loved. I can just imagine what the last change, to new versions of the Continental tires on the bike since new, will bring with their more modern compound and lack of 40 years of age hardening.

Below is the bike as it sits at the moment. The peeled paint on the tank is visible next to the filler. The new starter button fills the cigarette lighter hole below the left storage compartment on the fairing. And the non-spec master cylnder can be seen on the right handlebar. The silver paint on the forks, spokes, and engine cases are not stock...these should be polished but would require a level of disassembly I did not want to get into. Other than paint and striping the project is finished except for any normal maintenance items I find as I ride. It has been a fun and fulfilling project.

1977 Suzuki GS750 Restoration

Summary of Repairs and Restoration

Front to Rear

1. New front brake pads

2. Replaced front brake lines and fittings

3. Painted front caliper

4. Replaced front fender

5. Repainted lower front shock outer tubes

6. Replaced front tire

7. Paint front wheel spokes

8. Drained and replaced front shock oil

9. Painted front spokes

10. Replaced front master cylinder

11. Wired in new starter push button

12. Replaced rear view mirrors

13. Repainted tank gas cap cover

14. Replaced gas cap gasket

15. Replaced gas tank mount bumpers

16. Repainted and striped gas tank

17. Replaced gas tank emblems

18. Replaced side cover emblems

19. Replaced fuel petcock

20. Replaced fuel lines

21. Rebuilt carburetors

22. Painted carburetors

23. Painted engine and side covers

24. Drained and replaced oil

25. Replaced oil filter

26. Set valve clearances

27. Replaced rear master cylinder and reservoir

28. Fabricated remote rear master cylinder reservoir

29. Flushed and cleaned rear brake lines

30. Replaced rear caliper

31. Replaced rear brake pads

32. Replaced chain

33. Replaced rear wheel bearings

34. Replaced rear sprocket bearing and seal

35. Replaced rear shock absorbers

36. Replaced rear tire

37. Repainted, striped, and decaled rear tail section

38. Replaced rear turn signals

* Underlined items are outstanding

Pretty...and Pretty Close to Complete

1The word, like the music, is Italian. Literally it is the noun form of the word “work,” meaning the results of the verb “lavoro,” “to work.”