As someone who doesn't really like strokers I found it a bit strange to be screaming around on a Yam TZR125 that some reprobate had de-restricted and tuned. Judging by the way it'd put 90mph on the clock without any hesitation and could even breach the ton it must've been good for around 30 horses. By no means an exceptional power output for such a modern stroker.
That figure might be surprising to some, but not really that shocking when Honda could get the same power from a 250cc four stroke twin 25 years ago. You could ask what price progress if the same power couldn’t be produced from half the capacity, especially via the inherently more direct two stroke combustion chamber.
In the four stroke camp, 25 years has brought ever more reliable, powerful motors, at the price of massive complexity and only in recent years has much been done about paring mass and really sorting out the chassis, although some of the latest bolides become just as diabolical as a fifties Speed Twin if run on worn out tyres, needing hundreds spent on rubber every few thousand miles. Silly really, but I suppose it keeps the tyre factories in easy money.
The strokers, with the notable exception of some old Suzuki horrors (who mentioned the GT550?), emphasized the simplicity of their designs by keeping their mass within reasonable bounds; the rider free to ignore the call of steriods, weight lifting and the subsequent development of a physique so unnatural that it became impossible to sit on the bike without upgrading the suspension.
That's not to say that many of these devices actually handled. From the H1 Kawasaki's weak frame to the RD350LC’s dubious suspension, there was always an excess of terror associated with opening up the throttle in anger, even in straight lines in some cases. The dearth of seventies strokers on our roads has as much to do with the terrifying handling as the inherent lack of reliability of strokers, mostly down to a marginal supply of lubrication to the crankshaft, though there are many stroker fanatics who'll say, so what, an exchange crank doesn't cost much more than fitting a new camchain and tensioner to a four stroke.
It's very easy to become enamoured of stroker kicks, even in a small bike like the TZR. It was that directness of power, come 7000 revs, that had the front end of the 240lb Yam twitching upwards with unseemly haste even when employed in third. The combined trickery of induction and exhaust valves, electronic ignition, water cooling and modern oils made the stroker quite tolerable below those revs, though not really up to keeping mad buggers on CG125s, and the like, in sight. One blast on the throttle was sufficient to gain a complete advantage, the passing smokescreen usefully obscuring the number plate from invidious forms of police monitoring. Sleeping police used to be fun, as long as you saw them before you hit them; but cameras are a thoroughly despicable means of extorting money in the form of fines, but not that surprising from a government bankrupt of both money and ideas.
One of the disadvantages (if you want to keep your licence and knee-caps intact) of riding a flash little trip like the Yamaha was that every urchin on some oily heap just had to prove his manhood by showing that age, rust and high mileage were no inhibition to their forward motion through congested town centres. I blame the TV, their parents, advertising and, of course, a massive shortage of attractive women in the UK.
I wandered between extremes, popping along at moderate speeds and going throttle and speed crazy when the boredom and insults became too great. I usually ended up taking my quarry with the front wheel waggling around their helmet. It was not the kind of behaviour, I know, that readers expect from a mature and responsible citizen like their editor, but, hell, these little strokers get to you like that.
I think part of their strange need to race was that they figured the TZR was in 12hp form and therefore an easy target; an idea emphasized, I suspected, by my puke purple jacket putting me in the novice rather than experienced rider camp. Had the rain abated, had not the days been typically British - varying between bright blue skies and thunder clouds within a few minutes - I might've resurrected my leather jacket and probably been left to go my merry way without the constant stream of challengers.
The comics keep telling us that there are more new bikes being sold, and there certainly seem a lot more motorcycles on the road, but it's mostly old stuff, usually Japanese and occasionally British, that I keep having dices with. The new bikes must be there somewhere, but it's a rare day when I spot one.
There is a delight in screaming through stalled traffic at speed that has nothing to do with racing with other people; it's the kick that comes from shooting past fools who've paid utterly silly money for tin cages that can only move so slowly that the drivers would be better off getting out and walking.
Banning the lot of them would be the best idea, but I don't suppose that it's practical, you can just imagine the angst if the cagers had to cart their families around in sidecars. But something’s got to give, there are just too many cages in this country, ruining the roads, the air and their driver's minds.
In town the TZR is near ideal, then, with the useful bonus of cheap tax and insurance, fuel working out at 70mpg, an appalling fuel consumption for such a small bike but in urban commuting mileage is not so high as to make this much of an inhibition and it's no worse than most four strokes of similar power; more than anything else, the absurd running costs of a lot of motorcycles must put cagers off the game.
The only time I really hated the TZR was when it rained, then the combination of violent power pulses and worn Japanese rubber (the Japs are supposed to make the best condoms in the world, which is just as well given their violent and strange sexual proclivities, but I'm still not much swayed by their tyres, although their top grade radials are supposed to be better than most) had the back wheel sliding all over the shop and a certain amount of fear and loathing attached to touching the front brake lever, a normally quite excellent device that saved my tender frame from injury an embarrassingly large number of times.
I seem to be getting a bit old for the cut and thrust madness of major cities or maybe the city traffic has just gone even crazier with the passing of time and the way the poor old cagers are sent to an early grave with heart failure and sheer frustration; perhaps sensing that they are on the way out they try to take out everyone else on their path to oblivion.
Even in something modern and complex like the TZR, the two stroke engine is far from the zenith of its development. The way they are being redesigned is with direct fuel injection and the crank running on a proper, four stroke type, lubrication system. The latter giving longer life than the 20 to 25000 miles that most stroker crankshafts last, whilst the former should stop half the fuel being thrown out of the exhaust system, improving economy whilst maintaining power. The designers are more concerned with limiting emissions than improving economy, so they can sell the bikes in the States, though, so it'll only come about as a minor benefit. Most of this development is, strangely, coming from the cage world, which frugality apart is usually years behind in engine design.
The stroker stuff may yet go the way of the Wankel engine, brilliant in theory but a mess on the road. By the time the new strokers get on the street, if they ever do, the four strokes will have variable valve and ignition timing, which will give an excess of mid-range and top end power. Clever design ought to allow the rider to switch from full power to economy mode. Engines, of both types, will end up so complex that they'll have to be treated as sealed units that are thrown away when they wear out but should need no maintenance.
In stark contrast to the insanity of a stroker was a mild old Triumph twin, that most certainly couldn't be said to be maintenance-free. Mild in the sense that there was sod all power, but not mild in the way it buzzed the chassis and threatened to loosen all the fillings in my mouth. Luckily, this unfortunate interlude lasted all of three days when the disgusted owner demanded the bike back after I'd tried to ruin the damn thing by riding it across a field at 70mph. It was my quaint idea of a short cut, and it worked, too, as I was forced back to where I belong, on Japanese Iron.
Bill Fowler
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