Kawasaki KX250 Guide, History & Specs 1980 to 1989….. Kawasaki were a bit slow to catch up & join the motocross party in the 70s but finished the decade off in fine style with the twinshock 250 A5, production numbers seemed quite low for the A5 series so not too many around today. The 1980s were an interesting period in the development history of this iconic motocross machine & the bikes still make a good solid choice for riders  who wish to take part in Evo racing & I am glad to say that the attitude of “only a 1989 model will do” is changing as riders are now starting to seek out those early 80s models so that they can take part in the extremely popular Pre85 racing series. Remember these bikes are now quite old so you can`t always date a bike just by the colour of the frame, swing arm or wheel rims, remember newer style plastics & graphics can be retro fitted on to older machines so always double check the engine & frame serial numbers with a Kawasaki dealer or other reputable source before handing over any cash if you are thinking of buying an KX250.

Kawasaki KX250 1980-81…. The first & second model year of the then all new mono shock “Uni-Trak” KX250 are an extremely rare thing indeed, I can`t personally remember seeing one in action on a race track since about 1983, how many were imported into the UK I don`t know but surly one or two must still be out there waiting to be rediscovered. Back in the day the bikes looks & aircooled motor soon became yesterdays news & riders quickly moved on to other things, stories of frames breaking near the rear shock mount did not help things either although it has been suggested that more often than not this was down to poor maintenance by an owner, there were an awful lot more suspension components to keep greased & nuts & bolts to keep tightened up on the new mono shock machines than ever before. By all accounts the motor had fantastic low down & mid range punch so much so that it was not uncommon to see them turned into Enduro weapons, the tractor like power & light weight chassis were an ideal combination. The 80-81 KX250 are pretty much identical to look at, the most obvious difference is the swing arm, the original 1980 model had a regular square box section type design the 1981 version had an alloy swing arm that had the sides scooped out to form a capital “I” cross section. As I said before, a very rare machine indeed & certainly worth saving if you happen to come across one for sale at the right price, in the real world of clubman Evo racing a well sorted one will still get you into the thick of the action near the front of the pack, if you have the riding skills to match that is. Note if you do find one of these & are thinking of doing a twinshock conversion don’t bother, it will possibly devalue the bike & it probably won`t turn out as nice a machine as the earlier 1979 KX250 A5 twinshock model anyway, an easier to find & live with Honda Red Rocket would be a far better bet all round if it`s a twinshock machine you desire.

1981 KAWASAKI KX250 classicdirtbikerider.com


Kawasaki KX250 1982…. Oddly Kawasaki did not offer a big bore open class machine in 82, the KX model range topped out with the 250. The air-cooled motor rumbled on for another year although Kawasaki say the new centre port exhaust design, updated 8 petal reed valve & redesigned cylinder head have given us more bottom & top end power to play with. The engineers have also found time to produced a new chassis, stronger ” square section gold coloured” swing arm & pop a disc brake onto the front wheel, both of which now have gold rims . Visually the bike sports a o so cool at the time, rear side panel / mudguard combo & wears it`s front number board ,complete with air vents, at a strange “1981 Honda style” angle. If you are looking at a complete machine then its easy to spot all the differences & see it`s an 82 model & not an earlier 80-81 version. Note it was fashionable at the time to retro fit the new rear side panel / mudguard unit on to the older model so double check the year of the bike especially if you are looking at a basket case in boxes with bits missing.

1982 KAWASAKI KX250 classicdirtbikerider.com

Kawasaki KX250 1983…. First of the water pumpers, the colour scheme looks similar to last years model but other than that its all change for 83 ! After sticking with the same basic engine design with only minor updates for the last few seasons Kawasaki built a total new motor from the gearbox up so not much chance of raiding one of these to keep an older motor going. The all new motor had a good spread of power from the bottom up & suitable for both novice & demanding experts riders alike according to some testers, out front sat a redesigned pair of new 43mm forks while changes at the back saw new suspension including a single & stronger upright strut / link design to replace to old twin link set up, all this was held together nicely by a totally new frame. Its very interesting to note that Kawasaki yet again managed to build one of the lightest 250cc machines on the market, the new model was pretty much identical in weight to the old air-cooled bike it replaced, compare this to Yamaha`s increase of well over 14 pounds in weight when they converted their 250 from air to water cooled.

1983 KAWASAKI KX250 classicdirtbikerider

Kawasaki KX250 1984…. It`s interesting to see what gets changed on the first revision of a new model, automatically highlighting potential problem areas with the companies previous offering. 1984 saw Kawasaki make changes to the cylinder & engine cases, basically leaving more metal around the studs to strengthen things up, for the same reason there was an increase of 0.2mm on clutch plate thickness as well. Probably due to what the opposition was now offering to potential customers Kawasaki decided to get that relatively heavy flywheel spinning quicker, the cylinder head got a skim to raise compression, the exhaust port was made wider, the BTDC ignition timing was altered & a new 38mm Mikuni carburettor replace the old 38mm Keihin unit. A classic case of build something & then let your paying customers test it & discover the problems saw the radiators moved down & back a little on the 84 model, apparently these new fangled motors that everybody now made came complete with radiators mounted high up & had to carry quite a lot of heavy water, this in turn affected the centre of gravity & the turning ability of the new generation Evo machines. The result of all this tinkering created a sweet handling bike with a smooth punchy motor, very good for beginners & your average clubman racer but the expert riders were now demanding a motor that could get into the top end of the power range a lot quicker !

1984 KAWASAKI KX250 classicdirtbikerider..

1984 KAWASAKI KX250 classicdirtbikerider

1985 Kawasaki KX250….. The big news for 85 was the introduction of the new exhaust “KIPS” Kawasaki Integrated Power-Valve System, a complicated little device that depending on the engines RPM was either opening up to allow exhaust gases to exit the cylinder quicker for better top end performance or closing down to restrict gas flow & help boost bottom / mid range torque, Honda & Yamaha had already introduced their own versions so Kawasaki just had to join the party as well. Unfortunately all these years later it`s now viewed by some as just one more thing to go wrong on top of a complicated cooling & rear suspension system & an expensive thing to fix for todays restorers & racers. As you can see the rear number plate / mudguard unit had been junked & the styling of the new 1985 model was heavily based on Jeff Ward`s 84 factory machine & good news ! the KX topped the 250 shoot out tests “Especially in the horsepower department” in some of those all important American off road magazines. Let the good times roll !

1985 KAWASAKI KX250 classicdirtbikerider.com


1985 kawasaki kx125 kx250 kx500

1986 Kawasaki KX250….. At first glance it looks like little has changed for 86 apart from new seat graphics & new squared off radiator shrouds but no what’s this, the rear wheel now sports a disc brake ! It`s reported that this bike had identical frame geometry to the previous seasons factory machines & that Jeff Ward used a pre production 86 based motor instead of a full factory unit to win the 1985 national & supercross titles, so if it was good enough for him it will be good enough for any modern day Evo racer. Note of interest, the adjustable rear strut bolt was beefed up due to several failures on the ones fitted to 85 models, so owners of the earlier machine should watch out.

1986 KAWASAKI KX250 classicdirtbikerider.com

1987 Kawasaki KX250…..  The original sales brochure bellow gives the specification hungry enthusiast all the information they may need, the most obvious visual change to the 87 model is the new rear suspension linkage, the upright strut has now gone for good. It really must be said that from this point in the evolution history of the 250cc 2-stroke motocross machine that any bike made from the mid 80s onwards is a force to be reckoned with even when compared to far more modern equipment. To see a fully restored one in tip top condition, set up right & ridden by an expert rider is a sight to behold indeed. Light weight, easy starting, fantastic brakes & suspension, smooth power delivery, will rocket out of a start gate or corner in the blink of an eye, rail the toughest berm, jump as high & as far as anything else. Others may disagree & say later alloy frames or upside down forks made things far better but I am beginning to wonder if manufacturers have spent the last 30 years just tinkering & trying to improve on something that they had already perfected.

1987 KAWASAKI KX250 classicdirtbikerider.com

1988 Kawasaki KX250….. No doubt Kawasaki claimed that they had redesigned & improved this & that but the spec sheet reads pretty similar to the previous model. The most striking feature is the frame is now painted green, the fuel tank, radiator shrouds, side panels & seat have had a re style & for the first time in several years your new KX came fitted with fork gaiters.

1988 KAWASAKI KX250 classicdirtbikerider.com 15

1988 KAWASAKI KX250 classicdirtbikerider.com ..16

1989 Kawasaki KX250…. A quick spin through the spec sheet reveals a different carb & new thicker front forks, up from 43mm to 46mm. A closer inspection shows a new flatter profile fuel tank, the radiator scoop & swing arm graphics have had the annual make over & the tail pipe or exhaust  appears to have has grown a little longer. If you are wondering how the last KX250 model of the 1980s staked up against the rest then I can tell you that those well respected American shoot out testers thought that although the bike felt as big as a 500 it still negotiated the corners pretty well & the suspension was also very good. They found that the motor kicked out strong & super smooth power from the bottom right to the top. They came to the conclusion that they had no other choice other than to crown it the overall 250cc shoot out winner of 1989.

1989 KAWASAKI KX250 classicdirtbikerider.com 18

1989 KAWASAKI KX250 classicdirtbikerider.com 19

Conclusion…. As with any other manufacture a pattern appears when looking back over a particular models history, a complete redesign seems to be followed by a couple of years that only show minor upgrades to sort out any weak points in the original design, although companies seem to have the annoying ability to change quite a few parts just enough to stop things being interchangeable so double check parts compatibility before ordering stuff in. At the moment “2016” if you shop about & keep your eyes peeled you can still pick up a complete & running 80s KX250 for under £1000. It will probably need a thorough going through & don`t be surprised if you end up spending another grand or so on a suspension, wheels & motor rebuild but once it`s knocked into shape it will be as competitive as any other Evo bike. Of course once you do have a tidy, solid & reliable KX250 it`s then all down to you, as we all know motocross is more about rider ability & fitness than what machine you ride. Have you got what it takes to blast one of these to the front of the pack & keep it there ?……….Mr J

Please Note, the above is general guide only, please double check & cross reference information with other sources if you intend to purchase a machine. The only sure fire way to check the year of manufacture is to cross reference the Engine & Frame numbers with an official Kawasaki dealer or reputable parts supplier !