1975 Kawasaki S1 Rebuild: Installment Six

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The Triple is back on its feet, so to speak!

After a lot of scrounging, I was finally able to locate a set of tires for the bike. One thing I didn’t know going in – but do know now – is that it is hard to find front tires in the 3.25×18 (non-metric) size these bikes came with originally. I also own a ’76 Kz900 and have owned other old bikes and never had trouble finding tires, usually in stock. Not this time. The net had to be cast far and wide, and without the Internet, it could have taken considerably longer than the two weeks it took me. But, at last, success.

In a previous installment, I described my lucky find – the ’74 S3 parts bike I picked up for nothing (well, no cash – just a swap for an old gun I had laying around). Among other good things, the S3 had a nearly-perfect front rim, which after cleaning up looks almost as good as the (expensive) NOS rim I bought for the rear. The chrome does have some age patina, and a few of the spokes have some stains, but these are minor and I figured whey not use it and maybe later – after the bike is up and running – take it off, send it out for chrome and new spokes and all the rest. If need be. I think it looks pretty good and in fact like the slight patina, which may help the finished bike look more like a survivor than a just-restored machine.

I was also able to salvage the S3’s disc brake rotor, which I was able to return to NOS condition with a little detailing work. I light-sanded the inner hub areas and resprayed them semi-gloss. The machined surface of the rotor had virtually no wear – not surprising that the donor bike didn’t even have 3,000 miles on it.  A sad mystery that. The S3 was apparently just put into an alley and left to rot. Well, at least I have resurrected pieces of it – and they will have a new life as parts of my S1. That includes the front wheel, the disc brake (and the really nice original S3 caliper that only needs a quickie rebuild) and front forks, which have larger diameter lowers than the S1’s originals.

Another saved part (and saved money) is the S3’s front fender – which had to be used along with the S3 forks because of different mounting points (and geometry) but which I was happy to be able to use because it, like the front wheel, was in amazingly good shape, with very presentable chrome and the same patina as the front rim. The ensemble looks “right” – whereas I suspect that if I had to buy an NOS fender or have mine chromed, the newness of it would stand out too much relative to the wheel.

Out back, it’s a completely different story. The original rims – both my S1’s and the donor S3’s – were beyond salvation without major restoration. Rusted spokes, pitted rims and aluminum-rotted hubs. So I scrounged (and dug deep) for a “correct” NOS replacement rim, opting for stainless spokes – which will endure cosmetically for much longer than a set of the original-spec units. Now, if this were a museum-level resto, I would lose points because the stainless spokes have a slightly different finish – and the nibs are not gold, but the same (well, stainless) color. If you’re doing one of these bikes, you’ll have to weigh the same practical vs. “correct” considerations and decide which matters most to you. Either way, the end result will look great. It just comes down to how compulsive you are about exactly duplicating what the factory did.

The chain adjusters on this bike, like a lot of other small items, are specific to the S line and do not (as I originally thought they might) interchange with other period Kaws such as the Z1900.  The adjusters are smaller and use 8 mm (rather than 10 mm) bolts. They are also hard to find – like the S1’s 18-inch front tire. These come off the S3 and were saved from corrosion by the coating of oil they received from the S3’s oil-burner exhaust. This is one of the other great things about old two strokes: The oily exhaust leaves a film on parts that would otherwise be exposed to the air and elements and thus, rust. I was able to clean mine up with Brillo pads and elbow grease, followed by a light hand-sanding and polishing. They look brand-new/NOS.

Inside the rear hub went a set of new shoes – which were one of the few items that was an easy find. It was, however, necessary to do some down-and-dirty cleaning of the inside of the hub – which when first opened by me after years of just sitting was found to contain a large amount of whitish dust (aluminum rot), though luckily there was just surface pitting (which no one can see) and no physical-structural damage to the hub. After a thorough cleaning, I coated the inside with POR-15, a sealer that you brush on and which hardens to a ceramic-like finish, locking out moisture – and arresting further corrosion.

I also removed the pivot that actuates the brakes, cleaned it, greased it and re-installed it. Don’t forget this step if you want smooth, progressive rear braking action.

Of course, all internal bearings (and seals) were replaced with new items; ditto the (48 tooth on the S1) sprocket. The chain is in hand, but will stay in the drawer until the engine is back in the frame.

One small detail item that I think makes a world of difference is re-facing the tachometer and speedo. If you’ve owned an old bike – at least, owned one that sat outside in the sun for years – you’ll know the faces will be faded and look tired.

Take a look at this gnarly specimen!

Luckily, there is a place (Repro Decals) that sells high-quality and absolutely “correct” vinyl facings for most vintage motorcycles, including my S1. The process is simple. Well, sort of simple. The one tough part is (gently!) prying open the metal trim rings that are pressed on by the factory and which you have to remove in order to disassemble the gauges. I did mine by – gently – wedging a small flat-blade screwdriver underneath the lip, then patiently working it around. Use and up and down motion – not side to side – or you’ll leave ugly bend marks. There will still be evidence of your work, but (in the case of the S1) the underside portion of the trim rings will be completely covered by the rubber gauge hoods once installed on the bike – so no one will be able to see anything. 

Ok. Once you have the gauges disassembled, you gently pull off the indicator needle, set it aside, then (again, gently) unscrew the two screws holding the face in place. Originally, the numerals and so on were screened onto the facings, so you’ll need to sand them off – then prime/paint the metal faces with flat black paint in preparation for the new decals. It is important to let the freshly painted faces dry for at least 24 hours before attempting to apply the decals. I waited 48 hours. Remember: You will only get one shot (applying the decals) and if you mess up, you’ll have to start all over – and buy another set of decals, too.

Application of the new decals is straightforward but does require some skill. I put the faces in a glass-bottomed baking pan, then lightly misted them with warm water that had been mixed with a drop of dishwashing soap. This will enable you to move/position the new decals before they take a set – and tear, if you tried to move them again. Gird your loins – and act quickly. Slide the decals into place, making sure all the holes are lined up right. Gently squeeze out any air bubbles (if necessary, you can prick these with a pin later on; the small hole will not be noticeable). Once in place, gently tamp with a dry terry cloth towel, being extra super careful not to nudge the decal out of position. Put the faces somewhere safe and leave them to dry completely/cure for 24 hours.

In the meanwhile, you can re-bopp the needles. On the S1, these were originally finished a fluorescent orange; this easily reproduced by (after gently sanding them) spraying 2-3 light coats of fluorescent orange paint. I’ve compared my work to known “factory” and NOS gauges and I can’t tell any difference.

Reassemble the gauges. Don’t forget to (if necessary) clean and polish the glass. Be sure it is free of smudges on the inside before you recrimp the trim ring! I used a rubber-resto product (Back to Black) on the hoods, which brought them back to as-new look. Previously, I had stripped and re-painted the gauge housing semi-gloss black. Ready to rock! In the accompanying gauge picture to the left, you can also see the freshly installed NOS handlebar and (re-used, factory) tie-clips for the electrical harnessses, which make everything neat – and “correct.” 

The headlight bucket presented an interesting small problem. I ordered what was marketed as an exact replacement housing – because my original (and the S3’s) was in really bad shape, with dents and such that would have taken a lot of work to fix. But the replacement, though very close, turned out to be slightly larger diameter where the headlight assembly itself bolts in. The S1’s original sealed-beam light is kind of oddball in that it’s not a plug-in, plug-out unit. It has its own weird little harness, that plugs into the main bike harness. I did not want to cut any of the factory harness, and I wanted to use the “correct” S1 headlight (my original factory unit still works). So I slightly modified the inner ring that holds the light in place. It is not obvious to the eye and everything works as it should. I mention this in case you come across the same issue with the reproduction buckets on the market. 

Final item for this installment: A note about exhaust. Or rather, a comment about the dilemma I am facing. I have the S1’s original pipes and they are in decent shape physically (see earlier comment about the virtues of oily exhaust) but the chrome is too deteriorated to just re-install them. It’s the restorer’s ancient problem: The nicer the bike is, the crappier the stuff that’s not nice looks – and the more noticeable it is. Such is the situation with these pipes. I would like to have “correct” factory pipes when this project is done, but that will likely mean either sending my originals out to be re-chromed (major expense – and also, major work/hassle, especially trying to remove the internal baffles, which have been in situ for pushing 40 years now). Or, buy a NOS set – which I don’t even want to  know the price of right now, even assuming they’re findable, which they may not be.

Or – option three – ditch the factory system and go with something like this. These are, more or less repros of the vintage-era Denco chambered pipes that were money back in the ’70s, when triples ruled. Not cheap, either – but less than a NOS factory system and probably also than the cost of restoring my originals. I’ve gotta think on this – and will keep you posted.

Meanwhile, on to the body work – which I will be farming out. I want a perfect result – and I am a far from being a perfect paint man. My side covers and tail are in good shape – other than needing paint (Halibut Blue). But the tank is going to need some work. It is not rusty or dinged but some idjit Kreemed it (badly) and that stuff is peeling off inside. It will need to be boiled/sealed and all that before it gets painted. I will keep you posted on this, too. Look for Installment 7 – within visual distance now of the finish line!

Throw it in the Woods?



  1. Anything that looks nice/new/Shiny! and works better, not just cheaper would be my choice. You want to ride that bike, not just put it under a glass cover, right?

    When events conspire to make true resto out of reach go for the mod!

    • That’s my thinking on this one, too!

      But, first things first. I’ve gotta get the tank/bodywork in motion, then I can start on the engine… also have a few loose ends yet to tie down, including the front brake (total rehab needed; all new lines, rebuild kit for the master cylinder and everything new for the caliper except the castings… amazing what 20 years of just sitting can do to brakes!)

  2. Very nice, Eric. As a fellow moto-head, I’ve been eagerly following your progress with the S1 resto.

    With respect, I do have one minor semantic quibble with the following:

    “I was also able to salvage the S3′s disc brake rotor, which I was able to return to NOS condition with a little detailing work.”

    A NOS part is, by definition, an original factory production item that was never put into service. It needen’t look new; e.g., some shelf wear is acceptable. A used part can be refurbished to look new, as you’ve done, but it cannot honestly be classified as NOS due to its prior usage.

    Perhaps you meant to type “NOS-like condition”?

    • Thanks – and yes, correct! Right you are!

      PS: I just got through disassembling the caliper… lawsee. What a mess! Thanks, previous owner, for never changing the brake fluid. I was able to clean out the castings using rifle brushes and steel wool…. but the piston is so gouged with rust I doubt it’s usable. I have a rebuild kit on order, but it just has the soft parts… know anywhere I might find a piston for this puppy?


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