R1200S and ST Base Runs and Comparisons With Older Models - Written Sept ‘06

As is the policy of BMW Australia these days, every shop has a demo of all the new models sent out before the models actually hit, which is a rather good idea.  And, as such, when said demos get past the first service I usually take the opportunity to zip them down to the dyno to see what they make.  As someone who owned and loved the previous model sport boxer – the R1100S – I was keen to see how it had changed.

You don’t have to ride too far to notice how much lighter and responsive to input it feels.  Nor do you have to open the throttle too far to know it’s quite a lot faster, especially when you get some revs on it.  I tend to be a bit sceptical of the BMW claimed outputs, which, like the new Ducati power rating system, seems to not correspond to closely with the Dynojet result.  BMW claim 122 for this model, whereas they claimed 98 for the 1100.  The graphs below show they’re not quite there, but it is a very significant increase.  Green is 1100S, red is 1200S.  Power first, then torque.  Both bikes are in std trim.

Yes, it really does have 20 more hp.  The performance changes to the engine, like the other 1200 hex head series engines, are two fold.  More power through bigger valves, higher RPM limit, etc, and less rotating mass.  Plus the balance shaft and counterweighted timing gears to make them smoother too.  On the road it translates to lifting the front wheel in first gear without provocation, and can be somewhat scary when you do provoke it without thinking too hard, as I found out.

As the torque curves show, it makes much more high RPM torque than the previous model, and this is what gives the power increase.  It feels very nice on the road, and really likes to be revved.  With the surprisingly low cost Ohlins optioned in, it’ll be a very nice road bike in the same way the 1100S was, but faster and more suited to the track day end of the scale.  Some will complain about the lack of touring ability, but that’s the way it goes with traditional BMW customers it seems.  Something they’re trying to change with the newer, sporty models, but it will take a while.

And, if you‘re after a touring edge, the 1200ST is the model that replaces the R1150RS and partly the 1100S.  The first time I rode the ST I was quite impressed with how nice it felt on the road.  I’d say (as have many others who have owned the 1200ST and 1100S) that it out-sports the 1100S, as well as being more comfortable and faster to boot.  Looks a bit funny at first, but that grows on you (or doesn’t) and you can’t see what it looks like when you’re riding anyway.

The next graphs show the 1200ST compared to the 1100RS and 1150RS.  Green is 1150RS, blue 1100Rs and red 1200ST.  You can see the ST curve is less linear than the two RS’s, probably due to the different style exhaust and higher performance orientated tuning.  The peak torque numbers of the ST are quite a bit higher than the RS’s, more so than the increase in capacity only would lead to, which is contrasted by the two dips in the curve.  Power first, then torque.  Again, all bikes are in std trim.

Just like the 1100 and 1150 RS spec engines, the ST engine doesn’t require it to be revved right out to give good performance, making good power all the way through the RPM range.  It’s quite a nice engine to use.

Next we’ll compare them all on one graph.  1100S is green, 1200S is red, 1200ST is blue, 1150RS is yellow, 1100Rs is pink.

You can see the ST is better than the 1200S up to 6,500 RPM, but then the top end power of the 1200S takes over, just like the engines feel on the road   Given their respective design briefs, it’s what you’d expect.  In terms of all round power output, they’ve come quite a long way since the first of the 4 valve boxers (1100RS).  Considering that, as an engine design, it’s well outdated and has the fundamental problem of the airflow going along the same axis as the crank, and not across it, it’s an impressive evolution.  And although it’s an outdated design, as a combination of engine design and model suitability to air cooled cylinders sticking out the side it works very well.

With the exception of high lean angle of course, but then again ground valve covers always have an air of cool about them.

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