1975 Kawasaki S1 Rebuild: Installment Five

Print Friendly, PDF & Email

The old Kaw is starting to look like something again … something good. At last!

This latest progress reports begins with a short story about a lucky find. I happened to be down at my local bike shop, buying some items for one of my other bikes, when I mentioned to the counter guy that I am trying to resurrect an old S1 triple. He smiled and said, “You need to come out back with me.”

So, “out back” we went – to the alley behind the store. Bunched together in the dim light were at least a dozen old bikes, including a purple RD350 and several old Kaw triples. “If you have something, like an old pistol, you might want to trade for one of these . . .” said Scott – the parts guy and my new best friend. Long story short, I swapped one of my old hoglegs (a serviceable Taurus Millenium) for a parts bike ’74 S3 400. As many of you may know, the S3 and S1 share numerous common parts; in fact, there are some parts on the S1 and S3 that aren’t used on the S2!

You can’t see the gold I found in this picture, taken after I’d already scavenged many of the good bits (including two perfect condition side covers that would have cost me at least $75 each on eBay) but as you will soon see, I got a sweet deal!

But, let’s back up a little.

Before I found the S3 parts bike, I had reinstalled the swingarm (with new bushings in the shaft as well as cleaned/painted end caps) onto the frame, along with a set of new/repro shocks that duplicate the originals almost exactly, right down to the integral red reflector. I still need to locate the rear grab bar, which is the same on both the S1 and the S3 but not the same on the S2. These are hard to find and expensive when you do fine one.

Next came the centerstand, along with its spring – polished a little for some contrast shine. I haven’t gotten around to the side stand yet; it’s on deck for my next Blaster session.

I also got a set (four) of repro turn signals and stalks to go with them. Well, I got one out of three – for the moment, anyhow. For some reason, when I ordered the four, I got one correct style and three not-correct style (with the wrong stalks). The company rep was very nice about it and promised to send out the three correct items right away.

So, now, about that S3 parts bike… .

As soon as I got it home and did a little cursory cleaning I discovered I’d gotten lucky. The parts bike’s front end – which, being an S3 front end, has a disc brake as well as beefier fork lowers – was in shockingly good condition. Take a look at the wheel. It’s almost perfect. Excellent chrome, even the spokes are still nice and the hub – with the expensive (if you have to buy a NOS piece) disc in fantastic shape. A little sweat work and this rim will be showroom. And it hardly cost me anything; just an old gun I haven’t used in years anyhow.

For obvious reasons, I’ve decided to swap in the S3’s front end. In addition to less work, I will end up with a better front end (being a fairly big/heavy guy, the larger diameter forks are going to make this bike ride/handle better with me in the saddle). I also just saved a small fortune. Not having to buy a NOS front rim and new fork tubes (upper and lowers; the S1’s originals are junk) has put at least $500 back in my pocket. I know this for a fact because I did have to order a NOS rear wheel (plus spokes plus the labor to string the wheel) for the bike – and that alone is going to cost me at least $500.That’s not even getting into the forks… if I’d had to buy new forks.

Now, I don’t have to!

Here’s a shot of the S3’s forks, light-sanded and polished. I still have some more work to do, but they are already looking sharp and even better, the guts are good. The upper tubes are fine and the internals, including the seals, ready to go. All these forks needed was some cosmetic TLC (free; my labor) and a pair of new dust boots – on order from Z1 Enterprises. Since the donor bike had less than 5,000 miles on, there was no discernable wear on the internal springs.

Here’s a shot of the original S1 forks next to the S3’s forks. You can see the S3’s lowers are obviously larger diameter. They each take about 7 ounces of fork fluid, by the way.

There are other small differences between the S1 and the S3’s front end. For example, the fork ears. On the S1, they are stamped steel painted black; on the S3, they’re chrome. My originals were junk and I had been looking on the Net for weeks for a restorable set because mine – being bent and severely rusted – weren’t. The S3’s chrome fork ears are almost NOS perfect – so I’ll be using them instead. FYI, Kaw People: These ears seem to be identical to the ears used on the Kz900 and Z1900 (I have one to compare). Ditto the fork dust boots. This may help you if you are trying to restore a triple but having some trouble locating parts; check/cross-reference Kz900 parts; some are definitely the same on the S1, S2, S3 and probably also the H1 and H2.

Another small difference is the triple clamp lowers. The S3’s has banjo-bolt fittings for the disc brake lines,  and since I wanted to upgrade my S1 to disc brakes, I had to strip/clean and paint the S3’s triple clamp lowers. The uppers are  the same on both bikes, by the way – and if you wanted to stick with just the S3’s forks and use the original S1 drum brake set-up with them, you could. If this were a museum-spec. resto I’d have stayed with stock but since I do plan to ride this bike when it’s done, I think having at least one semi-modern disc brake is probably a good idea. (I will keep the original front drum hub and parts for just-in-case/down-the-the road).

So, next step: Strip, prime and paint the triple clamps and related bits and pieces. Here are some shots of that, along with the finished items. I ordered some reproduction (new chrome) hardware beforehand, so as to have everything on hand when it came time to re-assemble the front end. These bolts are readily available from several suppliers, incidentally – and reasonably priced. For example, the four bolts that secure the handlebar clamps cost $22. Each part was taken down to bare metal before being primed, then painted with three coats of gloss black.  

Now it was time to start putting the front end back together. If you haven’t done this job on a vintage ’70s Kawasaki  you’ll be interested in this part. Hopefully, you will have put a bucket or large catchpan underneath the triple clamps/steering shaft before you took everything apart. If not, you probably spent a lot of time on your hands and knees scrounging for the dozens of loose ball bearings that rained out of the steering head as you pulled the shaft. After collecting all these ball bearings, you will probably need to clean them of varnish and such. I found a good way to do this is by washing them in a glass with some Brillo pads. Just work the pad gently over them as you rinse with warm water. They’ll look new in about 15 minutes’ time. 

Having taken care of that, it was time to put the triple clamps back together. I used my finger to swab bearing grease on the tuliped portion of the triple clamp lower/steering tube – which holds them nicely in place during the install process.  On the other end, at the top of the shaft, I did the same thing, then I eased the assembly into place, dropped the race on top, then the large threaded “hat” on top of that and, viola – almost ready for the fork tubes! (Note: I did not tighten down the upper collar at this point because I’m not yet ready to slide the fork tubes – and fork ears and related small parts – into place. If you torque down the upper collar, you’ll never get the fork ears in and have to start all over.)

Here is the mostly completed front end, with the triple clamps in place, along with the fork shields and reflectors. I haven’t installed the forks yet because I’m still waiting on the dust boots and have some more polishing work to do besides. But as you can see, it is “almost there” – and within a week or so, I hope to have the entire front end finished, including the wheel with new tire on it. I haven’t yet inspected the S3’s brake caliper, which I hope I can rebuild and re-use. But if not, it shouldn’t be too difficult (though probably won’t be cheap) to locate a good rebuildable core or NOS unit. Once again, it appears to me that the S3’s caliper is the same part as used on the same-era Z1900 and so that ought to make finding a core/rebuild kit – or NOS unit – fairly easy.

I also installed the two-stroke oil tank, frame rubbers and spare spark plug holder assembly, which sits under the seat, just behind the battery box. The spark plug holder was another item pirated from the S3 donor bike that was in near-new condition and in much, much better shape than the part that came with with my S1 originally. The S3 even still had the rubber strap that secures the spark plug holder in place! Plus a good battery box. Plus a nicer inner fender/mud guard (and chain guard) than I had at first…

PS: If you look closely, you’ll see the seat pins – which came with the near-perfect seat pan that also came with the S3. Did I also mention the S3’s tank is cherry? I’m gonna have it boiled out by a local radiator shop, then seal the inside with Kreem.

Other items from the S3 that have found a new home on my S1 include the gear shift lever and rear brake lever, both of which turned out to be in near-new condition once I got the grease and some light surface rust off them. I was planning on sending out my S1’s originals to be chrome plated but given that I have a set of nice originals, decided to go with those instead for both financial and cosmetic reasons. New chrome is nice, of course, but the pieces would be clearly shinier than the stock bits, which have a more polished steel look to them as they came from the factory.  

So, things are starting to take shape. The S1 is now recognizable as a motorcycle again, something that has not been the case for the past several months. My wife begins to see potential – and isn’t questioning my sanity as much as she was.

It won’t be long now before I have a rolling chassis… and just in time as it’s getting cold already and it is nice to have most of the “outdoor work” – sandblasting, especially – done and out of the way.

Look for the next installment soon!







  1. Hey Eric!

    You need to take a look at the Caswell website (www.caswellplating.com). They sell a tank sealer that’s miles ahead of Kreem: epoxy based and guaranteed ethanol-proof.

    They also sell polishing supplies, powder-coating stuff, and plating kits, including zinc plating kits for things like fasteners and other small parts. I used one to rehab the fasteners on my old 450 Ducati. The results were beautiful. I plated the parts and them dipped them in a passivating solution that gives them that authentic bluish tinge.

    There’s a lot of other stuff, too. Check it out.

    Also, instead of trying to find old fork stanchions in good shape, you might want to try Forking by Frank, also on the Web, which makes new tubes for just about anything for very reasonable prices. And Buchanan’s is an excellent source for high-quality spokes and rims.

    Good luck!

    • Hi Steve,

      That’s a great tip – thanks!

      I’ve been using stainless fasteners I’ve scrounged from (yes, believe it or not) True Value – but being able to re-do the correct originals to the proper patina is definitely preferable.
      On the forks: I lucked into a very low miles S3 400 parts bike that had a set of (among other things) near-new condition forks. I ended up transferring the entire S3 front end (with disc brake) to the S1. Just needed some clean-up.


Please enter your comment!
Please enter your name here