another spy shot in color:
DrxBMW,
This morning I found the brand-new motorcycle newspaper "MO" -Special edition BMW motorcycles"
(special edition #37, April - June 2011) in my postbox.
It contains a 5-page thrilling report on the new motor with REAL pics taken from the prototype cast crankcase, heads and so on.
Anybody who is able to buy this, should buy it. I personally have no doubt that this prototype motor shows the real new watercooled boxer that will be shown to public in fall 2012 and that will arrive in the dealers' showrooms in spring 2013.
The whole motor is more compact and lighter, despite of featuring a water cooling system. There will be very few water hoses as most of the cooling canals are situated within the crankcase - visible from the outside, but internal.
The crankcase is divided vertically, the cylinders and the crankcase are one part, similar to motors like the Honda VTR1000F / SP-1 and SP-2. Good idea to keep the crankcase stable and stiff and the cylinders short. Downside: Makes tuning and motor revision harder and more costly.
Cylinders and heads still have cooling ribs, and what should I say, I like that design VERY much. It looks more compact, lighter (which it will be) more sporty and absolutely modern, but it still keeps a lot of the old BMW boxer heritage.
The intake ducts are flipped over, from the rear where they were now about ~70°-75° upright. The outlet is ~180° opposite, facing down and a little bit (~15°-20°) forward.
The pics of the cylinder heads show radial mounted valves (as the HP2S got already) but -thanks to the upright intake ducts- with a REAL DOHC and a lower valve angle. Valves might be a little bit bigger as they were in the HP2S.
Combustion chamber and ducts look kind of ideal, there is a single 10mm spark plug thread in the center. Combustion chamber is so compact with such big holes for the valves that there will be no possibility for a 2nd spark plug.
The oil reservoir shows up very slim - it seems the manifold will be wound very narrow around the crankcase.
Cams will perhaps be actuated by gear drive (!) but only from a middle shaft that is been driven thru an ordinary chain from the crank.
The new crankcase is said to have three (!) main crank bearings, but unfortunately the pics don't show everything, so I can't say if there is a middle main bearing. Also there were no pics of the crank.
It's quite a sensation that the new water-cooled boxers won't have a separated gear-box. In fact the gear-box is integrated, there is one oil circuit lubricating the gear-box too and there is a "wet clutch" with multiple clutch discs, although the clutch is situated in the crankcase where it used to be. Newspaper announced that the gear-box will be built by a BMW-joint-venture enterprise in china and not by traditional supplier GETRAG from germany - what a pity.
Oil reservoir is small and slim because now a fair amount of the oil will also be "stored" in the gearbox.
Inlet ducts are not round but rectangular, so they should be bigger.
Newspaper is speculating about a bore/stroke ration of 100x75 or 102x75 or 102x78mm.
I personally think this is rubbish. Bigger ducts, bigger valves, a water-cooling system, a REAL DOHC all that indicates that the motor was invented to produce a lot of hp. So I personally think it is likely that pistons will be bigger than before (old 1200 stock: 101mm) and perhaps that the stroke might stay the same or even get a little bit "shorter" than old 1200 boxer motors have.
Why should BMW use smaller pistons and a longer crank for such a modern motor ?
I'm hoping for a 104x73mm which would lead to 1241cc
A sport motor would be possible with a 104x70.5 giving it 1198cc.
Dean O
Founder San Jose BMW,Cali
