Starting up, the engine screamed at 4000rpm on the choke, the plastic vibrating and the motor rattling away like the valves needed doing or the camchain tensioner was on the way out. Needed a good ten minutes to warm up and quiet down. If I tried to use full throttle before then it would just stutter away and make nasty noises. Probably down to the baffles burning out in the original silencers; the black downpipes also heavily spotted with rust the first time it rained - it wiped off with a rag! The fasteners did a similar trick, the bike needing a lot of tender loving care to keep up its appearance. That probably explained the look of relief on the past owner's face as I roared out of his driveway.
The bottom line on the GPX was 90 horses, 430Ibs and 150mph. What I call cheap speed! I felt a little perched upon the bike, the plastic not sculptured to make one feel part of the experience. The bars and pegs, though, were nicely placed for both town: work and speeding. The saddle was badly shaped - or worn out - my thighs lacerated after about half an hour. Sloping forwards, the braking had my groin thrown into the petrol tank until I learnt to grip the back of the tank fiercely.
The engine screamed fearsomely between 7000 and 11000 revs, zooming off so fast that I nearly sprained my ankle on the gear change keeping up. It didn't like running below 3000rpm, and only made a moderate amount of power up to seven grand. The first time I rode it, I was thinking it wasn't much to write home about (or even to the UMG) when it hit the power band and my whole perspective on life was radically changed. If I wasn't quick on the gear change the tacho needle would bury itself into the red. It may well be more civilized with intact baffles.
When the GPX was introduced sixteen inch front wheels were still popular, all kinds of theories offered in the press about their advantages. It was only when the Japs started fitting seventeen inchers that the journo's actually admitted that the new bikes they had so praised had in harsh reality been somewhat twitchy. There are two ways of looking at this - either you enjoy the fast turning nature of the bike or you complain about the bars shaking in your hands from time to time. Not having much choice in the matter, I decided on the former, found that a bit of optimism applied to forward motion worked wonders - though it sometimes felt like the front wheel was trying to fall out of the forks it never actually developed into a wild speed wobble, circa H1 mythology.
Good tyres help - I like Pirelli's best, which last 5500 miles front and 4750 rear. Acceptable. I wouldn't even think about running on bald tyres in the dry, let alone in the wet - there's just no built-in safety factor to compensate for dead rubber; even when everything's in its prime it feels right on the edge. After three months I noticed a rather serious weave at 140mph. Investigation revealed slightly worn Uni-Trak linkages. The shafts weren't quite seized in solidly, a few solid whacks with a sledgehammer freed them off nicely. They were totally free of grease, explaining the shot bearings. I also did the swinging arm bearings as I had it all apart. No grease there, either! Very naughty. If you leave it too long, it can turn very expensive with new shafts needed.
Some misguided designer fitted the rear caliper on the bottom of the swinging arm where it was perfectly positioned to pick up all the road crud. As I had the back end apart I thought I'd take a look as the back brake had always been poor. I shouldn't have bothered because the only way I could get the partially seized caliper apart was with some serious hammer work - so serious that I broke the casting. Breakers found the idea of their having a working replacement quite amusing but I persisted and was given something off a GPz600R that fitted on top of the swinging arm. A bit of lateral thinking sorted that. even if the brake was still a pile of manure compared even with a rear drum brake.
In contrast, the front discs never gave any trouble once I became used to the need to never to use more than two fingers on the lever. It was dead easy to lock up the front wheel, skid off the road and add to the accident statistics. Pads lasted over 6000 miles, relatively easy to fit. Whilst at the front end it's worth noting that the front mudguard was designed to allow the maximum amount of water over the rest of the machine. A definition of stupidity, that can't help the bike's finish.
Another piece of nastiness was trying to get at the cylinder head. Took about an hour to get the petrol tank and plastic off, only to find that one of the spark plugs was obscured by the plumbing. I'd deduced that the plugs needed doing when it started taking four minutes before it'd catch from cold - it's not the kind of job to do by the roadside. Dead easy to strip the plug's threads. The good thing about modern, water cooled motors is that their huge complexity does give them good resistance to neglect - I never quite convinced myself that it was necessary to check the valves or balance the carbs; the GPX didn't complain in any way that I noticed.
The only other bit of remedial maintenance needed was a bit of welding to the exhaust cans - if I'd left it any longer they would have fallen off. The engine made a wonderful snarl when it came on the cam that had milk bottles leaping up and down in applause. I always gave the neighbours a dose when I charged off to work at 5 o'clock in the morning. One of them's a cop, a nice bit of revenge!
After seven months I was used to the acceleration and handling, felt I'd had the best that the bike could offer and it was time to move on to something yet faster (ZX-10!), The GPX went for fifty percent more than I'd originally paid, which more than compensated for the work I'd put in. They are still on offer for reasonable sums; cheap speed personified!
Dick Williams