17 May 2012 | Guido heads into the shed looking for trouble - and find it
There’s an old saying that if it has wings, wheels or a keel, it’s going to be trouble. Overly cynical? You would hope so. But, reluctantly, I have to add a ‘rider’ to that, which is that if it’s old and has an engine, it will eventually try to empty your wallet. How old? Ah, well, that’s the part you can’t predict.
A good case in point is Grendel the 1980 GSX1100ET, a toy I bought as a fun runabout about a year ago.
Under normal circumstances, these air-cooled 16-valve engines are utterly bulletproof, with an exceptionally strong bottom end. For years, they were the powerplant of choice for modifiers and drag racers, because you could extract outrageous horsepower without killing them.
I’ve owned an ET before, which had had absolutely nothing done to the engine but a chassis that was fettled to within an inch of its life. It turned out to be a quick and ultra-reliable mount. So you can imagine my disappointment when, despite my best attempts to ignore the problem, I had to admit that Grendel was sick.
WHAT’S UP, DOC?
You didn’t need to be a rocket scientist to realise something was amiss. The thrashing noise from the top end was obvious – even though the engine was running just fine – and it was getting worse. If there was any lingering doubt, all I had to do was to dust off Kate the Katana, with a very similar engine, and start it up for a comparison. It was dramatic. The Kat was whisper quiet by comparison.
My default workshop is Melbourne’s Stafford Motorcycles, in part because they’re walking distance from my house and because I trust them. For these old Suzis, my next obvious choice would be Mick Hone Motorcycles, a few suburbs away, which has an amazing stock of Suzuki parts along with a wealth of knowledge on the marque.
So, it was off to Staffords. Owner Don and mechanic Ash are often bemused by the variety of machinery that issues forth from my shed – to the point where I’m beginning to suspect I’m one of their chief forms of entertainment.
Anyway, they agreed Grendel was not a happy camper. My theory was a stretched camchain. With 79,000km showing on the clock (heaven only knows how much it’s really done), a tired top end was possible.
Now the one thing you don’t want to hear is the bloke who owns the workshop ringing up and saying, "It’s bad news, mate." It brings up visions of last rites being performed on your bike, or your wallet, or both.
It was revealed the cams were losing their hardening, in turn chewing out the rockers and some of the carriers. Ugly. Very ugly. The good news was we’d got to it before the destruction turned from being major to catastrophic. A little more use and it’s likely the metal being torn out of the top end of the engine would have found its way into the bottom end.
Once again, Muggins is looking at a sick engine and working out whether it was worth fixing. Good parts availability for this series meant it was at least possible without resorting to hours of custom fabrication. As a car builder I once met offered, "You can fix anything, if your pockets are deep enough."
The rest of the Suze was reasonably sorted so what the hell, let’s do it. You’d question whether it was worthwhile if you were going to sell the machine, but this is a keeper.
In an ideal world, you’d rip out the carriers, cams and rockers and replace the whole lot with new bits. Not cheap, but the simplest approach. However, getting a matching set of everything wasn’t possible, which called for some ingenuity.
The main problem was the carriers, where the only realistic approach was to find a good second-hand set. Given they’re plain bearings, the concern is the used parts don’t do something ugly to the new cams.
Speaking of cams, the stockers were no longer available, but a later model set was. There’s no downside to this. They go straight in and you’re likely to pick up a little performance along the way. Suzuki started this engine out with an overly modest claim of 73.6kW (100hp) and quickly developed it into a 1135cc fire-breather with more like 91.2kW (124hp).
Luckily, a full set of rockers was also available.
Reassembly was straightforward enough but there were two concerns. Firstly, there was the matter of getting the new cams bedded in with the old carriers. Secondly, why did the hardening give out? This is almost unheard of in GSXs. Did this mean it had a blocked oil gallery?
In the end, a little fine machining was applied to the carriers to ensure a snug fit. The engine was given a number of brief runs with the cam cap off. Each time, the cam was pulled out and any high spots on the carrier were removed. This also gave plenty of opportunity to observe the oil flow, which was fine.
So what caused the damage? Ash’s belief is someone was probably riding it on poor oil and they let it run too low. His advice is to buy a good quality oil (Spannerman says mineral is perfect for these old engines) and change it every 3000km.
Oh, and after all of that, the camchain was just fine…
You know when mechanics are pretty damned chuffed with themselves. They haul you into their lair and demand you watch in wonder as they fire up the latest resuscitated transport of delight. Sure enough, Don and Ash presented the bike with something approaching a flourish and turned the key with a "listen to this, mate".
Yep, it sounded great – a very different motorcycle. The proof of course was in the riding. First impressions were great. It was definitely happier (they’d discovered the inlet cam timing was out by a tooth), quieter and back to what a good one should be.
People who ride these old buses for the first time are often shocked at how good they are. Loads of bottom end and midrange, smooth, a very healthy top end rush, with reasonable handling (so long as you’re not trying to break lap records). Get too cheeky and they will get out of shape. Though getting old, they’re a genuinely good ride.
So was it worth the trouble and expense? Yep.