Suzuki GS1000ST (1980)

After selling my first GS1000S back in 1995, it wasn't too long until I was kicking myself. So finally in September 2006 I went and bought this very original but somewhat weathered example for sale locally on eBay. In its favour were original (but faded) paint, a smoothie of an engine, and nice handling. Against? Well, let's just say there was lots of work to do.

I had a very enjoyable 2 1/2 years with this motorcycle. But I'm afraid the realities of family life meant that we needed two cars and not two bikes, so the GS had to go. A very sad day, but lots of joy for Neil the new owner.

So what's the big deal with the GS1000S? Well, they're a classic machine, great looks, good handling (for the period), grunty engine, bullet-proof, easy to maintain and work on. That bikini fairing isn't bad in the rain, either; you only really get wet from your knees down. Put simply, they're great touring machines. One day, I might get another [and I did]... but in the meantime, below is the list of everything I did while I had the bike.

Stuff I did (and struck off the list)

Running Gear

  • cleaning and servicing the back brakes (not a lot of 'feel'). This was just a straightforward cleaning and lubrication of the pedal hinge (it was half-seized with rust), and dismantling and cleaning of the caliper and its pistons. The tips of the bleed nipples were also corroded and pitted; I tried 'reconditioning' the old ones, but the things still leaked brake fluid slowly. So I ended up buying new OE bleed nipples, front and rear. The price was only mildly crippling...
    I also replaced the brake pads, as the old ones had been contaminated with oil. So much oil, in fact, that when I swung the blowtorch on them, they caught fire and burned vigorously for 5 minutes.

  • replacing bent front brake lever. I tried straightening it, as you always do. But it snapped, as they always do.

  • rust-proofing and sealing the fuel tank. It was pretty crusty in there, but the POR-15 tank lining kit worked a treat. That was the end of the rust sediment gunking up the carburettors.

  • replacing the rear shockies. I bought a pair of 2nd-hand Konis on eBay, which needed a few new parts — but no worries there, because they're a fully rebuildable shock absorber. Unlike the original Suzuki items which were still on the bike after 26 years, would you believe.

  • new seals and bushes in the front forks. Well I really gave this my best shot: I used 800-grade emery paper to polish the rust away, but there was one pit which was just too big. So I cleaned it out, and filled it with an epoxy compound ('QuickSteel'), which I have heard can do the trick on motorcycle forks. Well after a couple of years it was still fine, so there was no need to get the forks re-chromed. Which was a good thing, because re-chroming ain't cheap, trust me.

  • Braided brake lines. The brakes were pretty spongy; in fact, you could feel the lines expand when you squeezed the lever. Besides, trusting 25-year-old hoses was always going to be a bit difficult. So I fitted a top-of-the-wazza 'Hel' brake line kit.

  • Spacers to pre-load the fork springs. The front suspension was a bit on the saggy side — the pneumatics is a nice idea but the air always leaks out — so I put in a pair of 1" tubular aluminium spacers under the fork caps to add a bit of badly-needed stiffness to the front end.

Electrics

  • fixing the fuel gauge. Well I thought I'd fix this problem when I re-lined the tank. I extracted the fuel gauge sender assembly from the tank, and what did I find but that some enterprising soul had drilled a hole through the rear of the sender assembly. Now why anyone would want to do that is beyond me... but of course they managed to drill the hole right through the gizzards of the delicate wire coils (sigh). However, I managed to patch it up with careful use of the soldering iron, plugged it in to the appropriate point on the wiring loom, and voila, the gauge worked! Probably for the first time in 20 years.

  • fixing the horn. Replaced the missing button with one from some old Katana switchgear I had handy.

  • sorting out the charging system. When I first got the bike, the electrics were delivering no more than 12.5 volts. Finally I made the time to test the regulator-rectifier (RR). But when I took off the sidecover and looked at the wiring, it was horrifying: insulation had burnt off the wiring, and all that was left were a few green corroded copper strands. Frankly it was a wonder the battery was getting any juice at all. So I trimmed wires and removed ancient and troublesome 'bullet' connectors, soldered it all back together, and then it was charging at a healthy 14.5 volts. I couldn't believe that I'd snatched electrical victory from the jaws of defeat.

    And I shouldn't have believed it, either, because when I checked the battery (why hadn't I done this first? Shame!) it was as dry as a bone. Hmm... so I topped it up filled it up with demineralised water, and put it on the slow charge for 8 hours. Then when I fired the bike up, things were charging at a fairly ferocious 17.5 volts... yes folks, that means a fried regulator. Small wonder the battery was baked dry. So I installed a new RR from Electrex UK, and then finally it charged at a healthy 14 volts with the headlight on. So the stator and the battery were OK — really, I got off fairly lightly.

  • installing a voltmeter. With GS electrics being what they are (ie. borderline oompf at the best of times, and prone to dropping off the perch), I went and mounted a voltmeter on the rear of the instrument cluster, all very neat and tidy, using a homemade bracket. Removed it when I sold the bike.

Cosmetics

  • pulling the dent from the tank. You won't believe how easy it was — I used the trusty toilet plunger! I was so happy I nearly kissed it, but then remembered where it had been...

  • repairing rust in the seat base and reupholstering the seat. I got an old seat off eBay that still had a good base. Actually it turned out to be fairly rusty, but still servicable. I took off the rust with a wire brush on the electric drill, treated the base with phosphoric acid to convert the remaining rust, and then painted it with two coats of epoxy-based paint. I also reinforced the base with a couple of lengths of flat iron over the areas where the rust had reduced the thickness over the years. That made it as stiff as a board and ready for the foam and reupholstering. Then I managed to pick up a 2nd-hand but spotless seat cover on eBay. It fitted on really well and it looked great.

  • finding an original GS1000 grab rail on eBay. Naturally, everyone was chucking these things in the bin when the GS first came out... but now that we all want to restore them, the things are hard to find. So I ended up buying an entire seat with the grab rail still on it.

  • sourcing a centre-stand grab rail. This is the small chrome handle that sits immediately behind the LHS rear shock-absorber, and it's what you grab to help pop the bike on the centre-stand. It was missing from the bike when I got it, but thankfully they abound on eBay. (Did I mention I love eBay?)

  • new brake light lens. Ordered an after-market item from the UK on eBay. Perfect.

  • replacing the cracked perspex screen. Got the replacement made by Eagle Screens Australia, here in Kenwick, Perth WA. John gave me excellent service and made sure that the screen was spot-on in every detail.

  • repainting just about everything. Well that was the intention — but that work will now fall to the new owner. But I did manage to source a 'Suzuki' decal for the tail-piece.

  • cleaning and polishing acres of alloy. I forked out and bought a polishing kit (calico buffing mop that bolts onto the end of a benchgrinder axle) and have begun the time-consuming work of taking aways years of oxide from the clutch cover, points cover, sprocket cover, and alternator cover. A bit boring to do, but the end result is well worth it.

  • replacing those not-very-useful-except-for-looking-at-your-elbows mirrors. They weren't original, anyway (early GSX-R items) — so I sold them on eBay. Then my GSX1100EF-riding mate Paul kindly went and gave me a pair of bar-end mirrors. I used them on the end of the bars for a while, and got the usual excellent visibility. But as the GS1000S was my preferred bike for commuting around Perth, lane-splitting got a bit difficult at times with those mirrors waaaaay out there. I hunted around on eBay for a while, and eventually took a punt with a pair of after-market mirrors to suit 01-02 GSX-R's. After some minor modification of the brackets, they fitted on quite well. With their slightly convex mirror profile and reasonably lengthy stems, you got a fairly panoramic view of things behind you. They were also pretty vibration resistant, ensuring that plod remained in sharp focus at all times.

  • re-plating or replacing a myriad of rusty fasteners. I bought a set of SS engine cover Allen bolts on eBay. It was all good except the set was one bolt short... so sourced an M6x85mm bolt from Westfield Fasteners — a top online shop with just about everything you'd require fastener-wise on a motorcycle.

Engine

  • general tune-up, oil & filter change, etc.

  • checked timing with strobe light. Not that there was anything to indicate that it might be out, but I have learnt not to assume anything when buying a second-hand machine.

  • new air filter. I replaced it with one of my oiled foam filters.

  • new spark plugs. This fixed the misfiring that was happening over 5000rpm — mate I love a simple solution.

  • cleaning out the carburettors. As expected, there was plenty of rust sludge throughout the carbies, which called for a total dismantling, soaking in carb-cleaning fluid, and blasting out with compressed air.

  • adjusting the carbies. For starters, they had been very incorrectly set up. The slides were open far too much, which meant that the engine wouldn't idle at the correct speed. So someone had set the pilot circuit to run rich in order to peg the crazy idle speed back! Which partly explains why the plugs were sooty black and the fuel economy was shot to pieces (like around 10kms per litre — same as a car!).

    But she was still running rich, which at first I put down to worn needle jets — but it turned out to be (mostly) the valve timing. That's right, SN models should have 20 camchain link pins between the timing marks on the camshaft sprockets, but ST's (such as this) should only have 19. What a difference it made: power and fuel economy were restored!

  • Unfortunately past tinkerers just couldn't leave the air mixture and pilot screws alone, so it fell to me to put them right.

    Helpfully (hah!), all my Haynes manual would tell me about the air screw and pilot screw settings, was that they were "preset". (Subtext: If you have been a naughty boy and tweaked them or found them fiddled with, tough luck.) Sigh... so it was that I fiddled around for weeks on and off, experimenting my little heart out but basically getting nowhere.

    But then I managed to jag an original Suzuki GS1000 workshop manual on eBay, and within 5 minutes of pulling it out of the packet the magic numbers were revealed: 1 3/4 turns out for the air screws, and 5/8 turns out for the pilot screws. Eureka! Immediately the bike's low down performance was transformed to what it should be: smooth and user-friendly.

    [And while we're at it, if you have a 1979 GS1000SN — with the Mikuni VM28SS carbies — the magic numbers are: 1 1/4 turns out for the air screws, and 3/4 turns out for the pilot screws.]

  • fixing the exhaust system and muffler. The bike was 1/2 choked by a DUD of an exhaust system it came with. I tried looking for mufflers on eBay, but they were just way too expensive, and aftermarket items from manufacturers here in Australia were off the scale of reasonable cost, too.

    So in the end I thought, Why not make my own muffler? I wanted something that resembled the original GS mufflers, ie. a long classic cone shape. After a bit of digging around on the Internet, I discovered that the dimensions of the classic-looking Dunstall mufflers were basically: 2" diameter to 4" diameter over a length of 2'. (Now in essence it's just a truncated cone, so the formula to translate this to a flat shape is quite straight-forward.)

    I ordered the sheet metal (1mm thick mild steel, ungalvanised), and cut out the relevant shapes accurately with a jigsaw. Then it was over the street to Ashley with his metal-bending machinery and TIG welder. It was all assembled around a 2" (51mm) diameter length of exhaust pipe, with fibreglass wadding to dampen the sound.

    Well, the end result was excellent! The muffler looked the part with its classic dimensions, it was reasonably quiet, and yet there was a nice note there as well. For more details, go to my muffler fabrication article on my tech pages.

  • installing stainless steel exhaust flange studs. The old rusty bolts holding the exhaust system to the head were barely doing the job. So I made up some studs from 8mm stainless rod — much better. Naturally, removing the old bolts wasn't straightforward; bolt #8 (WHY is it always the last bolt you go to undo?) decided to shear off, leaving a minimal stub poking out of the head. Sigh... so I spent the next 1.5 hours wiggling it free with the mole grips. Grrr.

  • fit an oil cooler. After having gotten my mitts on an oil cooler adapter, I tracked down what I thought was a suitable oil cooler on eBay and plumbed it all in. It all worked wonderfully until I realised that, under full compression, the mudguard clipped the lower leading edge of the oil cooler. Doh!! So I ended up tracking down a 2nd-hand GSX750EF item, and it fitted in there a treat. I also got the hoses routed underneath the fuel tank, so it all looked much neater too.

    Oil cooler adapters seem to go for silly money on eBay. If you'd like one at a more reasonable price, and take it from there.

  • cleaning out the sump and oil strainer. After racking up the kilometres these things can get pretty blocked up, slowing oil flow to critical things like the camshafts and crankshaft bearings. So I dropped the sump plate off, and there was the usual litany of horrors I have found in all the older bikes I've owned: tarry sludge, metal chips, aluminium shavings, small lumps and 'ribbons' of silicone, etc. The oil strainer actually wasn't too bad, but I removed it and gave it a thorough cleaning anyway. Of course, Philips-head screw #3 which held the strainer in place had to be half-butchered before it would budge. Why Suzuki never put hex-headed bolts down there is another little mystery. Anyway it was all now clean as a whistle and ready for another quarter-century of service.

  • top-end rebuild. After going for a ride with a mate on the GS1000S and me following on the Katana, I saw for myself the shamefully huge cloud of blue smoke whenever the throttle was rolled off, especially at highway speed. It was so bad that it was a wonder plod hadn't pulled me over.

    So the next day, my curiosity got the better of me and I pulled the top end apart. Hardened old valve seals and worn rings were the main culprits. Carbon build-up on the valve seats wasn't helping either. I had a motorcycle engineer measure up the pistons and bores, and to my relief a piston kit wasn't needed — just a hone and a fresh set of rings would bring things up to scratch. While it was all apart, I lapped in the valves, and generally cleaned things up.

    It all went back together easily, and started on about the 4th revolution of the crankshaft. Over the next few thousand kilometres the engine ran-in nicely, and you could easily feel the bike's extra grunt and willingness. No more oil being burnt, no more clouds of smoke, and plenty of extra horsepower. Bewdy! Engine rebuild page here.

  • replacing the cracked oil level sight-glass. I ended up buying a spare clutch cover off eBay, and swapped the good sight-glass for the busted one in my existing clutch cover. Swapping the sight-glasses was easy enough; they are simply a 'press-fit'.

  • new seal for tacho cable drive. Alas, the local bearing shops stocked everything except the 12mmOD/5mmID seal required — which meant I had to submit once again to the extortion that is the Suzuki parts counter. So, planning ahead, I ordered two of the suckers.

  • rebuilding the clutch basket. The old clutch was rattling away at idle, no amount of carb-balancing would get rid of it, so it was time to pull it to bits and set to work.

  • new starter clutch. These aren't exactly the best design feature of the GS/GSX Suzuki engines. After a while they disintegrate, and the rollers can shatter and the little springs get eaten, etc. So I forked out more hard-earned dosh at the Suzuki parts counter, 'coz no one else makes starter clutches, of course.

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Review article

When he sold me the bike, the previous owner kindly gave me an old Two Wheels magazine, complete with a review of the 1979 model GS1000S. The Two Wheels crew have given me permission to make this available online. Click on the thumbnails to view the successive pages of the article...

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Differences between the ST and SN models

Here in Australia, the GS1000S was available for two years: 1979 (the SN model) and 1980 (the ST). Below I've tried to list the differences between the models as we have them in Australia. If you think some of the info. here isn't correct, go ahead and email me, and if I agree with you I'll fix it.

Incidentally, if you take a peek at the carburettor, cam lobe, and valve timing specs below, you'll see why the ST has a bit more poke than the SN.

 

1979 GS1000SN

1980 GS1000ST

Paint colours

Blue & white; B&W pinstriping

Red & white, with a few blue & white models also; tri-colour pinstriping

Paint layout

Indicators

Die-cast aluminium bodies with chrome finish; round lens

Black plastic bodies; rectangular lens

Reg/rect.

Regulator and rectifier are seperate units

Regulator and rectifier are combined into one unit

Ignition

Points ignition

Electronic ignition

Seat

Fairly even height across entire length

'Stepped' seat, with higher area for pillion

Instruments

'Dashboard' which incorporates fuel gauge, temp. gauge and clock

No 'dashboard'; fuel gauge is incorporated into the face of the tachometer

Exhaust system

Mufflers extend to be level with the back of the rear tyre

Shorter mufflers which reach to approx. level with rear axle

Choke operation

Choke controlled by a cable attached to a push-pull knob mounted on the upper fork yoke

Choke controlled by a lever on the left-hand end of the carburettor assembly

Fuel tap

Conventional style fuel tap with 'Reserve' setting

The fuel tap has no lever; no 'Reserve' setting as such — the rider is expected to pay attention to the fuel gauge. Woe betide if he doesn't...

Brake discs

Plain with no holes

Drilled discs (ie. with machined slots for cooling purposes)

Footpegs

Set further forward

Set, err, further back

Gear lever linkage

Lever fixed directly to gearshift shaft

Lever connected to shaft via ball-jointed linkage

Front brake reservoir

Round type

Rectangular type

Wheels

Black/silver

Gold/silver

Horn

Single unit

Twin units

Carburettors

Mikuni VM28SS; pilot jet #15; needle jet O-4; main jet #95

Mikuni VM30SS; pilot jet #20; needle jet O-7; main jet #97.5; float level 22.4 +/- 1; pilot screw 5/8; air screw 1 1/4; ID no. 49120

Cam lobe heights
(rounded figures, mm)

Intake: 36.34
Exhaust: 35.79

Intake: 36.80
Exhaust: 36.30

Valve timing


When setting the timing (ie. with cylinder #1 at TDC), make sure that you count 20 camchain link pins from the timing mark on the exhaust sprocket, to the timing mark on the intake sprocket. [**See the section below on Valve Timing.] Of course, this is the case with pretty-well all GS1000's, except the ST — please see the next column!


For the ST, the number of camchain link pins you count between the timing marks on the camshaft sprockets is 19. [**See the section below on Valve Timing.] Now I know all this might sound a bit trivial... but let me vouch for the extra horsepower and fuel economy that were unleashed when I put it right.

Valve Timing for the GS1000ST

Here's a diagram — straight from the Suzuki workshop manual — explaining the specifics of GS1000ST valve timing, as distinct from the SN. Make sure you get it right! To be sure, check the identifying numbers on your camshaft sprockets.

**However, you should also note that here in Australia we seem to have got a fairly mixed-up situation as far as those sprocket numbers go. For example, my ST has got a '490' intake sprocket, and a '49S' exhaust sprocket. And, an ST I heard about in Melbourne has got a '451' intake sprocket and a '490' exhaust sprocket. What's going on, Mr. Suzuki??? Well, we can't be sure. Maybe they were just grabbing whatever sprockets were available in the parts bin when they were assembling our beloved Aussie GS1000ST's...

**But whatever sprockets you have, or indeed whatever model of GS you have, the main thing is that when you have cylinder #1 on TDC (top dead-centre) on the compression stroke, that the notches on the ends of the camshafts (coloured green in the diagram above) are directly facing each other, as they are in the diagram. If either of the notches are pointing away from the opposite camshaft, you know that the timing is out, and you will need to reset the camshaft(s) so that the notches will directly face each other.

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