BMW boxer engines

c-m · World Chat Champion Joined: 12 May 2006 Karma :

Had to start up someone's bike today as they're out of the country and want it started every so often and warmed up.

Anyway it was a big BMW K1000 something or other.

When idling, is it normal for it to be very viby and even rock the bars when on its sidestand?

When sat on and revved to 2000rpm is was silky smooth, but as the revs dropped back down to idle it there was quite a bit of vibration and the stationary bike seemed to throw a lot of weight to the left.

I've never been near a boxer engine before so i've got no idea about them.
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neatbik · World Chat Champion Joined: 27 Jun 2007 Karma :

Yeah that's normal for the R series engines.
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Tiff · Nitrous Nuisance Joined: 09 Aug 2006 Karma :

The Germans call them the gummikau- Rubber Cow.. Very Happy

Give em a real good blip of the throttle and they really rock and roll.
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Wafer_Thin_Ham · Super Spammer Joined: 18 Nov 2005 Karma :

They all do that sir.

Because of the longditutinal crank it makes the bike lean over to the left. If you really rev the tits off it, it'll feel like it wants to roll of the side stand. Laughing

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ToGGoT · Nitrous Nuisance Joined: 25 Jan 2009 Karma :

Well, the K-series is a flat-4 water cooled engine - the R-series are the 2-cyl boxer jobbies.

A lot of the K bikes suffer from terrible vibrations through the pedals at most revs, though the later, and better tuned ones are much better!

I rode my brothers R100GS once, and it was liked riding a tractor! Very throaty, and vibrations up through the bars as the engine revved! Great fun, but i can't say i'd have one myself!

In short, i think most BMWs of that age suffer from some sort of vibration or other!

ToGGoT
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Ariel Badger · Super Spammer Joined: 02 Dec 2006 Karma :

And they smoke on startup on the sidestand. I was playing with one this morning.
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stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

Moto Guzzis are even worse for it. People have been known to drop them when they blip the throttle at the lights if they don't have a secure footing.

I wouldn't have expected a K-series to do the leaning thing in any really pronounced way though, maybe a bit of torque reaction from the flywheel. The K-series are not boxer engines, that's the R series.

Mind you, the boxer engine always struck me as hell of a rough for an engine that should be in perfect balance (equal weight pistons 180 degrees apart).
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Tiff · Nitrous Nuisance Joined: 09 Aug 2006 Karma :

Having the engine in perfect tune makes a hell of a difference to a boxer- mine was pretty rough when I first got it, but a strip and rebuild of the throttles,a new throttle cable and a very exacting balance session made all the difference.
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1996 Kawasaki GPZ1100s,1996 VFR750,1980 BMW R80,1982 Kwak Z250B,1992 ZZR1100C,1996 BMW K1100LT,1994 Kwak ZZR600E,1993 BMW R1100RS,1992 ZZR 600D,1988 BMW K100LT,1998 Aprilia Pegaso 650,1994 Suzuki RF900,1991 Yamaha XJ600, 1988 Honda Dominator,1992 Kwak KMX125,1987 Yamaha RD50MX,1984 Honda MBX50.1984 Honda Superdream 125