At first glance it might seem mad to sell a hot GPz400 and buy a relatively staid XS400. But the XS was immaculate and cheap; had nothing to do with the earlier sad twin, this one the business with DOHCs and much superior spine frame. Surprisingly, the ’83 Yamaha was only short by 3 horses compared to the Kawasaki, with 45hp at 9500rpm and seemed to have a touch more torque at lower revs. It also had a 25lb weight advantage at 375lbs, and with its narrower aspect didn’t lose out on top speed acceleration, although ultimately it ran out of steam at 115 rather than 120mph.
For such an old motorcycle its condition was most surprising (this was 1994), its low price due to everyone thinking it was the awful earlier model and not bothering to turn up. A couple of bikes were sold by the official importers who for unknown reasons then dropped the range. Mine came via the grey import circuit, with just one UK owner who had done 2000 miles in a year. Excellent value. The Yam required a lot less throttle madness than the Kawasaki but to really shift still needed to be wound up to about eleven grand through the somewhat finicky six speed gearbox. Fourth gear was elusive, catching in a grinding semi-neutral or slamming straight into fifth.
The gap between third and fifth was huge, a massive drop in revs resulting if I tried to avoid fourth. New oil helped a little but it was a chronic fault, though one that didn't get any worse. I had noticed it in the test run but it all being a bit new to me assumed it was down to a nervous foot on my part.
Just to make life interesting, the clutch also slammed the bike forward when let out, needing a bit of work on the front discs to stop the bike going into a giant kangaroo leap. This was easy enough to learn but appeared to have a serious effect on the longevity of the brake pads - 6000 miles a set. The pads are similar to the XZ550, if you ever have to order a set. At least the back end’s served by a trouble free drum brake. Rear discs on moderate speedsters are just fashion accessories, not worth all the trouble they cause with gummed up pads and seized calipers. Get rid of them!
I'm going into a rant here because a little bit of winter riding did in the front calipers. Junk, junk, junk. Perhaps they don't have salt and acid rain in Japan. I slung the bike to the back of the garage in disgust - well, I wanted an excuse to avoid the cold, wet and icy weather. Finding cheap replacements was impossible! The couple of grey importers I phoned up quoted over a hundred notes for two sets of calipers. How to turn a moderate biker into a spitting, snarling madman!
Nothing for it but to persuade the old ones to come apart. New seals, sliders and pads were cheaper than a night out in Wrexham. I enjoyed the reassembly, nice clean parts but when I went to bolt the caliper to the forks one of the threads stripped! Crap Jap alloy, comes up again and again whenever you want to do some serious work. Drilled through the boss, used the thread and a nut and Araldite. Only problem, if I ever need to take it out again, I'll have to drill the bolt out!
Spring came in with a bang. Weather like summer! Out on the bike, big smile, laughed my head off at all the poor cagers who didn't have a clue in the massive traffic jams. Then a bit of rain. They were laughing now, the XS misfiring and cutting out. Barking away like a dog with a broken leg. Nasty piece of shit, I thought. I pulled into a fuel station, bought some WD40. Sprayed the plug caps, some plastic crap. OK, no more misfiring for five miles then it was back again. More WD40, no more misfiring for ten miles. Then the sun shone and my spirits soared.
A few weeks later the WD40 didn’t work any more. Screaming abuse at the bike had absolutely no effect. I ended up buying XJ550 coils, leads and caps. No more misfiring - for a while. Then it came back again, this time in the dry as well. I thought, do I want to check out the carbs? No, I didn't. Something simple for me to play with? A mate suggested checking the fuel tank cap for a clear air vent. It was clogged up. The bike ran like a dream after it was cleaned out.
Any twelve year old bike is going to give minor hassles. It's like a game in which you have to suss the problems before it has you off or raining hammer blows down on the machine. The next little hassle was the exhaust's cross-pipe becoming full of holes (with 13000 miles up). The XS runs very cleanly when all is well with the mill, but it seems if anything goes a little out of tune then it turns as irascible as the XZ550 - remember that nasty V-twin? Best not to!
The useful torque between 4000 and 7000 revs now did a runner, the exhaust going into its barking routine. Backfiring on the overrun was hilarious, guaranteed to have you shot on sight in Belfast. Old codgers were taken back to their war years, going into a defensive posture and doubtless overloading the NHS's mental facilities with stories of armed insurrection in the shopping precinct.
A mate was persuaded to point his welding gun at it and the moron vaporized the wafer thin steel so there was nothing left. My panic subsided when he suggested welding over the open sides of the downpipes. Better than paying two hundred quid for a replacement.
The result was better than before but not perfect, with a bit of a hole in the powerband between 6000 and 7000 revs. This was OK as it made the punch at the latter revs all the more prominent and acceleration appeared all the harsher. The exhaust note was a touch louder, but judging by the rattles, caused as much by fast decaying baffles as the modified exhaust.
The feeling that the bike was wearing away under me was emphasized by the way all the chassis bearings went at 17000 miles. Someone was playing a nasty joke on me, or something. The bike was never the most brilliant handler in the world, the front end geometry making it a bit vague in the corners. But when the bearings went, the bike turned into a wild speed wobbler. Replacement head, swinging arm and wheel bearings fixed it.
The rear end’s controlled by a mono-track arrangement, inherited from the old TR-1 V-twin, by the look of it. Their bearings never wore out but it didn't seem to have anything on offer that was better than a decent pair of shocks. Like rear discs, these single shock arrangements are much overrated on ordinary bikes and they can be very troublesome. A rear shock costs a ridiculous two hundred quid; even breakers want fifty sovs for a suitable replacement. It was a bit on the soft side but nowhere near as bad as the stock GPz400.
I would have much preferred the XS400's engine in the GP's chassis (with the suspension mods) but I don’t suppose the two would mate together well or that the hassle would really be worth it. The XS had some kind of balancer system that made it smooth but not to the extent of the Kawasaki, although I soon became used to the background buzz. The smoothest part of the range was 5000 to 9500 revs, which gave good cruising options in top.
Of the two bikes, I think I preferred the four to the twin but if you want a slightly more relaxed time the XS is superior. With bikes of this age, though, it’s all down to what turns up, its condition and price. You can't be too choosy! I sold the XS after a year for £1375, so I came out a little ahead of the game on that one. Latest bike is a ZXR400, an altogether different tryst!
Pete Maine