Sunday 21 June 2020

Japanese Thumpers



There are many different kinds of Japanese singles. From the old and simple Yam SR500 (still produced in Japan) to the modernity of the Kawasaki KLX650. Few, if any, make real sense of the possibilities of the breed. Vibration limiting power and adding unwanted mass in the larger designs, whilst those mild of nature but rarely have any compensatory torque or economy. Only in the relatively. modern 250cc thumpers, where there’s little vibration to absorb, does the genre shine at all brightly but their cost, even under a competitive regime of grey imports usually limits the market.

The Japanese, themselves, have to take a lot of the blame. The home market dominated by the craze for retro style, little thought given to extracting that happy blend of fun, torque and economy in which fifties British thumpers so profoundly revelled (saving that it took a few years to appreciate their vibes). Ignorance is bliss, as usual. Also, Jap retro thumpers are sold at prime prices, having an effect on the pricing of grey imports; the cheaper ones usually well faded if not completely worn out.

The market's further confused by the penchant of manufacturers for dumping some neat and advanced thumper technology into highly strung trailster chassis, the resulting mess needing some extra work to make it suitable for serious joy riding - at least the need to make a passing stab at off-road credibility means that mass reduction goes in the right direction, at least on some examples

Other quaint habits of Japanese thumpers include cutting out at junctions due to lack of flywheel mass, difficult starting as it’s still an acquired art on bikes without electric boots, disintegrating electrics as most thumpers still vibrate when used in anger despite complex, power sapping balancer systems, and less than brilliant reliability despite the paucity of components (which in turn should, but rarely does, mean they can be made from lighter, higher grade alloys and steels).

Bear all of this in mind when trying to track down a good deal. Also, many singles, especially those used off-road, end up in a rather dilapidated state after just a few years of not particularly heavy abuse or high mileage. Nothing in their initial high cost is reflected in their relatively poor build quality, often new bikes overpriced by a factor of two; an astonishing feat only matched by the rapidity of their decline and depreciation! So a weird mixture of stuff on the used market, but plenty of bargains around to keep the keen shopper on a roll.


Of the 250 singles, both the Yamaha SRX250 and Honda GB250 stand out as worthy of note. Managing to blend low mass, reasonable power, good frugality and splendid style is an all too rare feat in Japanese motorcycle engineering. These grey imports come close enough but those over five years old, despite their low mileage (at least on the clocks), are almost always well worn out, both physically and internally. These elderly survivors are at least cheap at under a grand but the better deals cost twice that for bikes a mere two years old with less than 5000 miles under their wheels. Choosing between the two merely a matter of style - both the retro Honda and modern Yamaha having their adherents. Whereas the Honda can, along with the similar CBX250, suffer spontaneous combustion of its electrics, the Yamaha can blow its top end without much warning, but recent low milers, at around £2000-£2500 have no such concerns.

The CBX250 took over from the CB250RS, the older bike having gained a reputation as a sort of four stroke MZ, blending performance and handling in a package that was better than most of the Japanese 250 twins. Alas, the usual abuse, especially from despatch riders, ruined the engine in as little as 20000 miles. All but the odd one-owner, much loved, RS has disappeared off our roads on the back of its built-in obsolescence and being a one-time favourite amongst the DR fraternity. Chances are that any that turn up on the used market are just about ready to die, so treat with a degree of care.

The CBX250 modernized the RS in all areas, especially with its DOHC engine that it shares with the later GB. An excellent bike if you never want to go much above 90mph, it was hounded out of the market rapidly because it was priced at absurd levels when new. Relatively rare when new, the odd used one turns up for £500 to £750; occasionally twice, that in the more insanely rapacious dealer's showroom.

The 250cc market being the most popular in Japan, and the most suited to thumper technology, there are many variants on the same theme but none of them quite match either the Honda’s or Yamaha's merging of characteristics. Perhaps the most interesting’s the neon-classic Kawasaki 250 Estrella. Way over the top, for sure, its latest incarnation goes as far as having drum brakes at both ends as well as amuch better looking dual seat. Unfortunately, its quest for retro authenticity goes as far as providing the engine with a minimal power output (right out of the sixties) compared to more high tech designs like the GB250. Throw in relatively high prices, to make it more of a miss than a hit unless town work's all that’s involved.

The inspiration for the Estrella’s engine might well have come from the old Z200/250 mill. The Z200 managed to blend similar minimal power with unusual frugality and the kind of doggedness that marked old terrors like the CD175. Chassis rot as much of a problem as engine demise on the high milers that are still rumbling along. The odd cheap thrill still makes the grade unlike the Z250 which managed a relatively rapid engine demise. A trick it shared with the KL250 trailster version. Lots of cheap, sub £500 dross around.

Kawasaki tried to get modern, at least in its engine, with the KLR250 trailster, but early examples of this water-cooled DOHC thumper are best avoided as they had piston problems. Later engines, say post 1990, were a deal tougher but the bike was still held back in the sales stakes by lacklustre styling and high new prices. Off-road abuse led to a rapidly ruined chassis, especially the bearings, but that’s OK as you can pick up a recent one for as little as £1500 which still has an engine in good shape.

Early KLR600’s similarly had troublesome engines but by the time the 650 version made it to these shores most of the problems were sorted. It's neither as long-legged nor as long-lived as the Honda NX650, though, so only worth buying one if cheerfully cheap. High milers have doubtful engines and rotted chassis; some dealers give them a cosmetic tarting up and try to charge silly money for something that will barely make it out of town.


Kawasaki only managed to excel themselves in the thumper game with the recent KLX650, a splendidly minimal effort that exulted in forty, torque filled, horses, in a mere 350Ib chassis. Alas, it was also heavy on fuel, at an astonishing 40mpg, no doubt down to the complexities of absorbing its vibration, which wasn’t even perfectly done as it could still thrum when pressed hard. The 650's a great fun machine, desperately in need of some road equipment, and available in very nice nick in the £2500 to £3000 price range.

Honda’s less complex - air rather than water cooled - NX650 also stands out as an interesting piece of thumper art. Both more powerful and frugal than the Kawasaki it doesn’t quite have the torque loaded feel of the newer bike, but at least Honda managed to develop the XBR500 inspired motor into one of the toughest thumpers in the business. Worthy of at least 40000 miles, sometimes more than 60000. Expect to pay around £2500 for a reasonable example; many with minor mods to wheels and mudguards that make them rather more suitable for road abuse.

The old XBR500 has done a virtual disappearing act off our roads, though grey import GB400/500’s offer a viable alternative for those stuck in the classic grove. At least the later efforts delayed the XBR’s valvegear demise for several more thousand miles! Built-in obsolescence will eventually catch up with all three variants so make sure you don't pay silly money for anything with more than 30000 miles on its clock. All are competent for sensible riding and just about up to staying with the flow on our mad motorways.

Rather harsher than these road variants, the old XL and XR 600s had a merry way all of their own but their general off-road usefulness meant that the vast majority were thrashed to an early if honourable death. The only ones left sport a mixture of mods, especially to the engine, that make them dubious buys even at under a grand. The old XL600 shared much of its engine technology and subsequent maladies with the infamous FT500, a bike which uniquely showed how not to design a big single - just about every element was ruined by ill-considered engineering.

However, the dodgy handling could be fixed with a suspension upgrade, the flat track styling still looks kind of cute and you eventually get used to the thumper vibes. There's little that can be done about the mediocre performance and laughable lack of longevity. Less than £500 will buy a runner but expect to pay up for a replacement engine (many different makes and models can be force-fitted). There was also a Japanese market FT400 which had similar performance, less vibration and a touch better longevity - well worn grey imports at around £750.

Such a poor design from Honda was all the stranger insofar as they started the four stroke single ball rolling with the old, almost indestructible, C50/90 step-thrus and kept many a learner amused in the sixties with the likes of their CB100/125/150 OHC singles. All raw reliable relics that still turn up in the odd pile of boxes or remarkably ragged state. That series ended up as the CB100N and the pushrod CG125, both of which were more sophisticated in their running and no less longer lasting. Loads of cheap stuff around if you can take the lack of performance and laughter of serious motorcyclists.


Suzuki tried to replicate this plain and simple engineering in their GS125 thumper, managed to merge most of the smaller Honda's virtues in a more attractive package, though, like the old CBs it wasn’t without the odd mechanical demise when run for high mileages on old oil - big-ends and cam lobes being most notable in their weakness under these circumstances. But anything that has low miles or been reasonably cared for (1000 mile oil changes at the very least) is a reasonable proposition - there are some rather old ones still in good nick for under 500 notes.

Suzuki tried the same trick with their larger single, the GN250 but missed out on balancing its virtues. Awful styling and indifferent chassis build quality, along with a mere 20 horses, were never going to set the market alight unless priced competitively. The GN ended up discounted to less than £2500 in the last year of its life, still not exactly bargain priced when compared with markets outside the UK but a relative snap in good old Blighty. Even very recent ones can be picked up for around £1500 and the older stuff can be had for £500. Watch out, though, as both chassis rot and engine maladies after 20000 miles can be quite harsh. There’s probably a good motorcycle in there somewhere but, in this case, the factory’s clueless about releasing it. You may well find a well modded example on the used market that’s worth buying.

As long ago as 1978 Suzuki showed marked competence in thumper technology, with the introduction of the SP370. Here, all the old virtues of British thumpers were blended with modern OHC engine technology. Although there was only 30 horses on hand, it was at least backed up with a modicum of torque and the relative lack of cubes meant engine balancers weren't needed.

The trailster stance had the virtue of keeping mass reasonable at a mere 300lbs, and not being so extreme that a smaller front wheel and proper mudguards couldn't cheaply and quickly convert the SP into a useful roadster. The SP370 also managed exceptional economy for a Japanese motorcycle, around the 80mpg mark. Both the kickstart gear and cam rockers could give trouble but they are fairly obvious on examination. Few nice ones left, but if you get lucky (find one that was converted for road use) a good buy at around £750.

The SP370 became the SP400, with an extreme trail version, the DR400. The frugality did a runner, though it was still good by Japanese standards at around 70mpg, the engine was toughened up in its weaker areas but still lacked an electric starter - true to thumper form, starting was an acquired art that soon sorted the men from the boys. Anything decent still left running is priced similarly to the 370.

The SP series evolved - if that’s the right word - into the GN400, a street version with a rather mild nature that only appealed to OAPs who were generally unable to come to terms with the effort needed to start it on the kickstart. Chassis wear, especially the bearings, is pretty harsh, few have survived into the nineties. Again £750 will buy one of few decent ones still on the road, but it’s important to do a compression check on the engine as they can run quite well with the rings near the end of their life.

Suzuki's modern incarnation of singular excellence lives on in their DR350, though its pricing, at a time when the Bandit 600’s going for little more than £4000 is very questionable. The trail stance’s rather extreme, with a seat height up in the clouds, and its general excellence off-road means most were thrashed close to death from new. Not surprisingly, then, there’s used stuff available for as little as a grand, although you'll have to pay twice that to find anything remotely decent. As expected of a modern motorcycle, the engine’s as tough as they come, only having to worry after 30000 miles when the top end can go down. With 30 horses and a mere 240lbs, the DR manages to escalate thumper kicks to a new level; a cheap and cheerful road bike trying to get out! Poor starting when hot its only real fault, the later electric start models the better buy.


Yamaha managed a similar trick with their TTR250, a lovely piece of DOHC thumper technology, again lost to the horrors of extreme trail bike styling. A touch heavier and harder charging than the DR, it’s only been available since 1994 in Japan but turns up somewhat expensively on the grey/shadow import market (over three grand). The Raid version's a better buy because it has a lower seat and better equipment for street riding but extremely rare in the UK. Another lost opportunity. Yamaha also churn out the 225 Serow, another DOHC single but a rather more modest one than the TTR. Light of mass, at 230Ibs, but its lack of power at 20 horses holds it back from achieving true excellence.

However, for fast town riding it’s ideal and much better than the hordes of trendy scooters that the glossies would like to inflict on us (loads of advertising revenue, see). The long travel suspension’s especially useful over London’s pitted and pot-holed road surfaces. One of the grey importers was selling new ones at £3000 and the older used stuff starts at under a grand - they are well worn out, though, despite the apparent paucity of miles. The best value’s found in the 1994/5 models with around five grand on the clock at £2000. Watch out, though, for ones that have had their frames straightened out after off-road damage.

Curiously, Yamaha’s old trail flame, the XT350 had a bit of a reputation for bending its frame out of line when the going got tough. It could also ruin its top end. These elements made for mind blowing depreciation, making the good ones - which really just take a bit of effort to suss out - bargain buys. If you're really lucky you'll find one of the 17hp examples that hasn't been derestricted (by cutting out a bit of rubber in the manifold) and has thus had a very easy life. When going well, XT350's offer adequate performance allied to light weight, a little bit ahead of those immensely popular 250’s in the seventies, which shared its 30 horses but had much more mass. It’s not impossible to find one in reasonable shape for under a grand; but you very definitely have to know what you've doing or you'll end up with a pile of expensive if useless bits.

Yamaha's history in big thumpers goes all the way back to the XT500 and SR500, both of which gained many adherents along the way. Plain and simple OHC engineering was only extreme in the amount of vibration that occurred at high revs and for the sometimes short-lived piston ring life - definitely worth doing a compression test. Having said that, the XT500, in particular, was popular with riders who wanted to cross Africa, and the like. Figure most used ones to be well modified and almost worn out, but still not a bad buy for as little as £500.

The SR500 is a weird piece of kit insofar as it, along with its better 400cc sibling, is still churned out in good old Japan and sold to those after a bit of classic engineering! Minor mods to the motor ensure that the engine life, starting and low speed running have improved over the old model, which was finicky when new and bloody minded after some wear and tear took its toll. Mediocre looks matched with mediocre performance meant they weren't popular in the UK but that hasn’t stopped it gaining status as a kind of ultimate rat bike. For whatever that’s worth. There’s the possibility of finding one with an upgraded chassis, including suspension and brakes off an old BSA or Triumph twin, and newish engine (as breakers are importing recent stuff from Japan to tear apart in the usual feeding frenzy), as well as recent grey’s at around £1500.

The XT500 turned into the more complex and better performing XT550 but it was a bike that never caught on in the UK. Unlike the final iteration, the XT600, which in XT600E and Tenere forms is well worth a look. Long established, with loads of cheap used parts available, it’s still a good idea to check the motor with a compression tester because they can keep running whilst in a dire state. A huge range of stuff available, from veterans that have gone around the world, to much abused DR hacks, to prime meat that has only ever been used as a pose mobile. Two grand should certainly buy an excellent example of the breed, perhaps graced with a smaller front wheel and road biased mudguarding.


Although the air-cooled XT600’s still going strong, Yamaha also tried, and mostly failed, to modernize the breed with the water-cooled XTZ660 thumper. Though more powerful, it never seemed to have the happy edge of the older bike, its five valve head, balancer system and water-cooling not working so well together as might be expected from a company so expert in four stroke engineering; perhaps just too much vibration to absorb without ruinously affecting the power and torque. Paris Dakar styling’s close to passing the sick bucket but there’s a good road bike trying to get out. £2000 up for the decent stuff.

Another less than successful bike, the SZR660, based on the XTZ’s engine, was held back by a combination of odd styling and silly list price; ended up heavily discounted. Not a bad bike but one, like the equally strange Suzuki 350 Goose, that in its high mass and low power doesn’t take advantage of the possibilities of the genre. You might find a decent SZR for as little as three grand, worth it if you want to spend some time developing the potential of the bike.


A lot of thumpers, like the SZR, unable to offer a compulsive combination of qualities. Ideally, a big single should be cheap (£3000 new), light in mass (250lbs), reasonable in power (40 horses) but excessive in torque, handle sublimely on the back of the ability to mount such a narrow engine low in the chassis and add that final element of good economy (100mpg). Sounds impossible? Well, the old Ducati singles of the early seventies actually came pretty close but were let down by idiotic electrics, poor quality control and spurious reliability - all factors that the Japanese have well under control (for the past 30 years if we want to be nasty about it - why not?).

If you want a stab at perfection, our best advice is to buy a low mileage DR350, open up the carburation and exhaust, knock a few inches off the suspension travel and fit a smaller front wheel (plus road tyres). Should end up with something light, reasonably fast and not too heavy on the fuel. You can do this to most of the Jap trailsters. If you just want to buy something straight out of the showroom go for a grey import GB250 or SRX250, both neat pieces of kit that will have you wondering why you ever bothered with the bigger stuff. If you want to get really weird and have money to burn, hit Japan and buy a 1964 Kawasaki 250 SGT - which looks like a cross between a RE Crusader, with its unit construction, 18hp OHV engine, and a mini Harley Sportster.


Dick Lewis