Suzuki GS1000G (1981)

Spotted by my eagle-eyed partner in crime Pete, this GS1000G had been sitting in a shed for about a decade up Geraldton way. Trailered it back to Perth in early April 2017, and set to work right away.

Unlike my last 2-wheeled project, this one was pretty-much complete... but suffering from a fair bit of surface corrosion and the stuff that happens when any machine sits around for 10 years doing nothing. After about 2 month's sourcing parts, refurbishing umpteen items, and finally popping on a fresh pair of tyres, the 'Thundering Zucchini' was ready to face 'The Man with the Clipboard'.

Try as he might, he couldn't find a single thing wrong -- which usually means they'll keep looking until they *find* something wrong. But uncharacteristically he was a reasonable bloke, and all was well. Forked out for the ever-increasingly exhorbitant rego. fee, and scarpered off into the rainy afternoon.

Here's what's had to be done to get it to this point (in no particular order):

  • Total clean-out of carburetors, rebuild kits installed
  • New engine oil & filter; fresh gear oil for shaft drive
  • Cleaned and repainted the exhaust system
  • Installed a 'Uni' foam air filter
  • Starter clutch fixed (old one had sheared and broken the 3 mounting bolts).
  • New rubber inlet manifolds
  • Sourced new ignition lock and tank cap
  • Repaired dent in tank
  • Reconditioned the cam chain tensioner
  • New seat cover
  • Cleaned, checked and repaired the wiring loom
  • Cleaned out and refurbished fuel tap
  • After-market front brake master cylinder and lever
  • Cleaned out and serviced starter motor
  • Front brake caliper kits (seals, piston boots, & pistons)
  • Rear brakes cleaned and repaired
  • New steering head bearings
  • Replaced the front fork tubes (originals bent)
  • Rebuilt the front forks (cleaned out, new seals, damping oil)
  • Sump cleaned out
  • Correct sump plug installed ('original' was a 1.5mm pitch thread graunched into the 1.25mm thread)
  • Repaired stripped spark plug thread on #2 cylinder
  • New tank support cushion
  • New pair of tyres
  • Side grab handle sourced and installed
  • Cleaned and painted front fork yoke cover & emblem
  • New pair of ignition coils
  • New spark plugs, plug leads and caps
  • Carbs balanced
  • Minor tuning (main jets up to #125's, jet needles raised a notch, pilot air screws 7/8 turns out)
  • New handlebar grips
  • Cleaned up the rear shock absorbers
  • Serviced and repaired the tachometer
  • Cleaned and painted front mudgard
  • Replaced cracked indicator lens
  • Put together a tool kit

Kind of an exhausting little list when you lay it all out like that!

If I decide to keep the machine, it will get a pair of new rear shock absorbers and maybe a stainless steel exhaust system to boot. But let's get some kms on the clock before we get carried away. ;-)

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19 July 2017
Sorted out a gnarly, persistent problem with the carburetion on the GS1000G, and I share it here because whether you've got a 1000S or a 1000G or indeed any Jap bike with breather tubes for the carbies, then you may well encounter the same problem!

Basically whenever I approached 90kph or higher on the freeway, after about 5-10 seconds the engine would start hesitating and losing a bit of power. Yes you could wind the throttle on more, but it still retained that 'hesitant' surging kind of behaviour, instead of smoothly holding its speed.

After a few rides, I began to notice that whenever I moved into the wake of a truck or van, the problem would disappear! This could mean two things. First, that with a touch of load on the throttle from the wind resistance, the carburetion wasn't right -- probably lean. But raising the jet needles 1/2 a notch made no difference, and at lower speeds there was no hesitation with light throttle. Hmm.

There was another possibility which I had read about on other forums, but never encountered myself. Namely, that at higher speeds either a vacuum or a pocket of higher pressure develops near the ends of the carburetor breather tubes/ outlets. This in turn affects the fuel mixture. To fix the problem, you simply need to change the location of the outlets, so that they sit in a still or steady pocket of air behind the carburetors (or wherever).

So, noting that the breather tubes were quite long (I'm not sure if they were original length or not), I trimmed about 5" off each one. And TA-DAAAAAAAA, problem gone!


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