Πληθαίνουν οι φωτογραφίες και τα άρθρα ότι το επόμενο βήμα για τους κινητήρες της BMW είναι έτοιμο και στην έκθεση της Κολωνίας θα παρουσιαστεί ο 1250!
Μερικά από τα άρθρα που διαβάσαμε τις τελευταίες μέρες….
Technical details of the 2019 134bhp BMW R1250GS and R1250GS Adventure revealed
BMW’s R1200GS and R1200GS Adventure have stayed unshakably at the top of sales charts in the UK and much of Europe for years – and with the biggest update in years coming for 2019 they’re set to cement itself even more firmly in that position.
We’ve known for a while that next year’s GS will be an enlarged ‘R1250GS’ and now we’ve finally got concrete evidence of the changes thanks to a leaked set of technical specifications covering both the base-level R1250GS and the higher-spec R1250GS Adventure.
Ever since the 1170cc R1200GS appeared in 2004, replacing the 1130cc R1150GS, the adventure bike market has been on a surge and the big BMW has been its undisputed king. Updates over the years have improved it in every respect, most notably in 2013 when the GS gained a water-cooled engine, complete with a new chassis and styling to wrap around it. But the essential recipe has remained the same; thumping boxer twin, Paralever shaft-drive rear end, Telelever front suspension, lopsided headlights and, of course, the trademark beak at the front.
Unsurprisingly, BMW isn’t about to mess too much with a bike that’s proved such an enormous success, but it is continuing the process of gradual improvement and in 2019 the big change is given away in its name: R1250GS.
We now got 100% confirmation that this is going to be the new bike’s name; but the actual capacity increase is rather more than the 50cc that it implies. Where the existing liquid-cooled GS engine is actually 1170cc, the 2019 bike’s engine has a 1254cc capacity; an increase of 84cc.
In terms of performance, the capacity hike increases the 2019 R1250GS’s power to exactly 100kW (that’s 136PS or 134.1hp). That compares to 92kW (125PS or 123.3hp) for the existing R1200GS.
The 2019 R1250GS still reaches its peak power at the same 7750rpm as the R1200GS, but is sure to have a fatter torque curve, thanks in part to its extra capacity but potentially boosted further by the rumoured addition of variable valve timing. The simple sheet of figures that BikeSocial has seen doesn’t reveal whether the VVT rumours are true, but spy shots of a prototype 2019 engine show that the cylinder heads are notably different to the current model, suggesting that there could be some trickery within them.
As with the current R1200GS, next year’s R1250GS will also be offered as a restricted 79kW (105.9hp/107.4PS) version in some countries to suit local regulations.
You might have thought that BMW would accompany this bigger, revamped engine with a completely redesigned chassis and bodywork, but the indications are that the firm is pursuing a tactic of incremental improvements rather than radical change.
The figures we’ve seen reveal that in terms of its essential dimensions, the 2019 R1250GS isn’t changing much compared to the current bike.
At the moment, the normal R1200GS has a wheelbase of 1507mm, and according to the accurate specifications we’ve seen, the 2019 model’s figure is a near-identical 1500mm. The Adventure version has a fractionally longer 1520mm wheelbase, which is the same as the current model.
Those figures suggest the chassis isn’t being altered significantly, and it appears that the styling also won’t change much. The overall length of the base model isn’t changing at all – the 2019 R1250GS will be 2207mm long, exactly the same as the 2018 R1200GS – while the 2019 R1250GS Adventure comes in at 2270mm, just 15mm longer than the current R1200GS Adventure.
Width isn’t changing at all – in 2019 the basic R1250GS will be 895mm across its beam, while the R1250GS Adventure will be 980mm. The current 1170cc machines share the same dimensions.
Those figures strongly suggest that the styling won’t change a lot. While the new R1250GS and GS Adventure might get tweaks to the headlights and some of the plastic body panels, the unaltered dimensions hint that they won’t be significant ones.
Apart from the notably increased power and capacity, the biggest changes on the 2019 spec sheet are to the bikes’ weights and sound levels.
Next year’s machines will be significantly quieter than the current ones, with decibel levels dropping from 92dB to a mere 88dB. That indicates a new exhaust system at the very least, although the changes to the cylinder head and cam covers could also be muffling mechanical noises from the engine.
Weight-wise, both the R1250GS and the Adventure pick up 5kg compared to the 2018 R1200 versions. That means the basic GS’s curb weight, complete with a full tank of fuel, rises from 244kg to 249kg, while the R1250GS Adventure is upped from 263kg to 268kg, again with fuel (its larger 30 litre tank – compared to 20 litres for the normal GS – accounts for much of the increase over the non-Adventure version). What’s adding that 5kg? Well, some of it is likely to be in the new exhaust system and, of course, the expected variable valve timing system.
Interestingly, despite the significant power increase, the R1250GS won’t get a higher top speed than the current model. According to the figures we’ve seen the R1250GS will achieve 136mph and the Adventure will top out at 132mph, unaltered from the existing bikes. That suggests the gearing isn’t being altered for the updated engine. It’s good news, really, since an increased final drive ratio would dull the additional acceleration promised by the torquier, more powerful 1254cc engine.
There’s still a bit of a wait before we see the final R1250GS; BMW is expected to show the bike, along with a new R1250RT using the same engine, at Intermot in Cologne at the start of October.
BMW RT goes 1250 VVT for 2019?
This innocuous-looking BMW R1200RT hides a secret: it’s bearing a new version of BMW’s evergreen boxer twin engine that is believed to feature the firm’s first motorcycle variable valve system.
Caught on test near the firm’s base, the bike wouldn’t turn many heads but its telltale datalogging computer case on the luggage rack is a dead giveaway that it’s more than just a standard R1200RT. And closer inspection reveals that the engine is very different to anything we’re used to seeing.
As well as completely reshaped cam covers – which look suspiciously production-ready with their moulded plastic ignition wire covers – the motor features rerouted exhaust headers that have required the bike’s bellypan to be redesigned. It’s all done so neatly that it’s hard to escape the conclusion that this is a near-production machine. Up front, the headlight also appears to be mildly redesigned and there’s a massive TFT display in front of the rider, although this could be part of the bike’s testing systems rather than an update that customers will get.
When the new engine is introduced, there’s strong money on the idea that BMW will also be upping the capacity. Just as the Ducati Multistrada has been given a hike to 1262cc this year it’s likely BMW will be moving to around the 1250cc mark.
Given that the old R1100 was replaced by the R1150 and then the R1200, an R1250 is clearly the logical next step.
While the engine is seen here in the R1200RT – or perhaps R1250RT – tourer, of course it will also turn up in the R1200GS adventure bike and R1200R roadster. Whether similar tech will extend to the retro air-cooled R NineT range is yet to be seen.
With a completely new S1000RR also under development for 2019, BMW has got a busy year planned…
Above: BMW’s next generation S1000RR spied testing last summer
But all that cosmetic addenda is mere footnote to the engine rework. Fortunately, our snapper has also managed to grab a shot of a motor sitting all on its own, revealing the extent of the changes.
That shot shows that the main elements of the motor – the cases, cylinders and heads – are largely unaltered, at least externally. And that leaves just one rational explanation for the significantly reshaped cam covers; this bike is packing a variable valve system.
Rumours have been swirling for some time that BMW has been planning to add variably valve timing to its boxer twin. It’s by no means the first firm to exploit the technology, either – Kawasaki’s 1400GTR has used variable valve timing since it went on sale in 2008, and Ducati and Suzuki have since joined the party with the Multistrada, Diavel and GSX-R1000.
The logic is simple. Any engine with fixed valve timing is severely compromised when it comes to meeting both performance and emissions targets.
To make lots of power at high revs, inlet valves need to be opened early to let the cylinder fill properly, giving lots of valve overlap (the period where the inlet and exhaust valves are both open). But if you have lots of overlap at low revs, you get unburnt fuel escaping into the exhaust, with detrimental effects on the emissions and economy, not to mention poorer rideability.
By using a simple cam-phaser, which can rotate the camshaft in relation to the cam sprocket by a few degrees, altering camshaft timing, you get around this problem. So that’s probably what BMW is doing here.
It’s certainly what Kawasaki, Ducati and Suzuki have turned to. Kawasaki and Ducati both use hydraulic cam-phasers, using engine oil pressure to shift the camshaft in relation to the sprocket. Suzuki has a clever centrifugal system that gets around rules banning hydraulic or electronic VVT in MotoGP (the GSX-R1000’s system was first developed for the GSX-RR GP bike).
BMW also uses cam-phasing in most of its cars, having first introduced its own version of the system – dubbed VANOS – in 1992.
Above: the redesigned, variable valve lift cylinder head that Alpha Racing made
However, there’s a chance the BMW boxer being tested here is even cleverer than the cam-phased engines used by rivals.
As well as variable valve timing, BMW has extensive experience in variable valve lift. That’s where you vary the amount by which the valves – particularly the inlet valves – are opened. BMW’s own variable valve lift system, Valvetronic, has been around for well over a decade on cars. It alters the geometry of the rocker arms acting on the valves to change the amount that they’re opened.
Instead of varying with revs, like a cam-phasing system, Valvetronic varies depending on throttle inputs. In fact, cars equipped with the system have no need for throttle butterflies in their intakes. Instead, at idle the inlet valves only open a tiny bit, and when you accelerate they’re opened wider – giving the same effect as a throttle butterfly but with no butterfly to disturb the intake airflow.
BMW’s own boxer bike engine has already been fitted with a variable valve lift system that eliminates the throttle butterfly – just not by BMW. Aftermarket firm Alpha Racing revealed a prototype variable valve lift cylinder head fitted to an R1200GS at the Cologne Intermot show in October 2016.
Its figures showed that the variable valve lift heads fitted to an otherwise stock engine boosted power from 123bhp to 144bhp while simultaneously reducing fuel consumption and emissions. Those are the sort of improvements that are sure to get any manufacturer’s attention.
Given BMW’s own experience in the same field, could the firm be taking this route with the new boxer engine? Don’t bet against it.
Spy photos: BMH Images
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