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! To my mind, 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.

This turned my mind to 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 then affects the fuel level in the carburetors, and consequently richening or leaning out 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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