Suzuki GSX-R750: Our Bikes

Date 11.6.2013

Presented by
  • Motorcycle Trader

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Suzuki GSX-R750

LITTLE SURPRISES

You gotta love the ability of old motorcycles to spring little surprises on you. All too often you’ll unpack the latest idiotic purchase, only to be rewarded with it instantly marking its spot with large quantities of some essential fluid. I had a puppy that did that once – it was so pleased to see its new owner it immediately wet the carpet. Fortunately I don’t have that effect on everyone…

Gixx, my 1985-model GSX-R750, was doing pretty much the same thing. Lined up for a photoshoot with the modern equivalent, it started the day grumbling at low revs and ended it by running like crap. By the end of the week it was unrideable, while much of the fuel had mysteriously disappeared.

Its previous owner had warned me that it had a bit of a tendency to leak petrol if you forgot to switch the tap off, which a healthy one shouldn’t do. The tap, by the way, is a bugger to get to – hidden in a spot where you need smaller hands than mine to reach it and stronger hands than my daughter’s to turn it.

Anyway, it was becoming obvious there was an issue with the carbs, mostly likely with the float needles and seats. While the bike had relatively modest miles on board (about 50,000km), sheer age can wearout these items.

HELLO AGAIN

Call me lazy, but I was tight for time and was happy to sling the job to Melbourne’s Stafford Motorcycles, just up the road from where I live. Getting the parts was no issue. The flat-slide 29mm carburettors were a special thing in their day, but they’re simple enough things to work on.

Needles and seats still mystify me to some extent, as a visual inspection doesn’t always reveal whether they leak. Sure enough, ours had a tell-tale ridge in the needles, where they’d worn. And they were dumping fuel at a prodigious rate – some of it ended up in the crankcases, necessitating an oil change. However, I’ve seen sets from other bikes with similar wear, which have kept on sealing. Go figure…

If you need to replace them, do it as a full set of seats and needles. Anything less is just asking for trouble.

As it turned out, the rubbers connecting the airbox to the carbs were looking tired and cracked, so we shouted it a new set. This is when I was very glad to have dumped the job in someone else’s lap. The rubbers just did not want to co-operate, and needed to be individually warmed up and softened with a heat gun before being coaxed into place. That little effort took up more time than the carburetor rebuild and resulted in Ash the mechanic adding to what I suspect is an already comprehensive and colourful lexicon.

Something else that had got my attention was the mysterious appearance of a spot or two of hydraulic fluid around the handlebar area. This is not a good sign. A quick look revealed no issue with the brake line, so I cheerfully ignored it until the bike was dropped off at the workshop.

Ash the mechanic discovered the clutch line was on the way out and was only a flex or two from complete failure. Naturally we replaced everything, including all the brake lines – it was a timely reminder that it really is worth checking the hydraulics on these old machines, which I confess I hadn’t.

We replaced the lines with a Goodridge product that was new to me: braided lines with black rubber covers. The idea is you get to keep the original look but get the neefit of the steel lines. They work well and are a clever option for the restorer who plans to ride the end result.

BACK TO HEALTH

So far we’ve given it a full service, new tyres, rebuilt the carbs and replaced the hydraulic lines. All up, we’re probably looking at a cost of about $1500 at normal workshop rates.

To me, it seems a pretty typical sorting bill for a recent acquisition. I usually count on at least several hundred for a decent-sized multicylinder bike, by the time you get it up to full health. Even with the best of intentions, owners who are thinking of selling have a tendency to let things go, most commonly servicing, drivelines and tyres. If it’s been sitting for a while, you can start to add things like fork seals to the list.

That’s fine if you expect it, but potentially a nasty shock if you’re not.

As for the Suzi, it’s now a much happier camper and a delight to ride. Even now, it feels light, sharp and – once you wind up that powerplant – surprisingly punchy. Claiming a little over 100 horses (73.6kW) for a 186kg dry weight, it should.