Boxer Engine Is it the perfect motorcycle engine?

[hep303]

I did a lot of studying before I bought my 04 R1150R. I chose this bike mainly because of the engine. I'm not a real hands on mechanic, but I am an enthusiast for all things mechanical. When I thought about all the pros and cons it seemed clear to me that a boxer flat twin has advantages over a V twin and other fours. There's no denying that modern Japanese 4 cyl engines provide insane power, but here's what I found to be the advantages of the boxer. I'm eager to hear other's opinions.

It has the lowest center of gravity

It provides greater stability because of the wide cylider heads and greater balance.

The vibration is minimized as a result of the equal and opposite momentum of the pistons.

It cools better than a V-twin because of the airflow over the cylider heads

It provides safety in a fall as the Cyliders will offer some protection to the rider

The only negative I can think of is it isn't so pretty. Unimportant in my book, but maybe not to some.

What have I left out? Boxer aficionados, add your comment. Am I just a BMW snob?

The only question I can't figure out, assuming I am right about all the advantages I have listed is: Why don't other motorcycle manufacturers use this engine? Why is it only a tiny fraction of all engines on the road?

[Gaston]

I find the Boxer engine is beautiful and distinctive. You can see it coming and know what their riding. And I don't really need that extra power, this thing is enough of a rocket.

On the low number of these engines out there, I think it is two parts, people idenify this engine with BMW and most people want what is common or 'normal' which is a V?

[DJ Downunder]

I agree....now if only they could make them sound like a V twin....wouldn't that be good.

DJ

[towerworker]

I love my '03. I bought it because I simply had wanted one since I was a teenager. (a long time ago)

It's distinctive, it's quiet and it's reliable. Nearly 4 yrs old now and still gets alot of positive comments in parking lots.

Wayne

[GTR350cc]

You are a gifted and discerning individual; blessed with keen insights into the fundamentals of what makes motorcycling special. The only flaw in your statement is that boxer engines are, in fact, beautiful.

[paroyboy]

Love my boxer but as for best design of an engine, I'd have to say Moto Guzzi. The engine is sideways so you get the increased cooling but it's still a "V" so you get the personality of a "V". Guys over on the Guzzi board say the boxer engine is just an old Guzzi whos jugs are sagging!

[celticus]

"The only negative I can think of is it isn't so pretty. Unimportant in my book, but maybe not to some."

I think it is VERY pretty! There are some would not agree with me and there are some who don't like wimmin, chocolate and beer either. So I guess it is just a matter of taste in all three cases.

Mark

[munchmeister]

I like the looks because the boxer is distinctive. Recognizable from far away; when you see one you know what it is without looking at the badge. I love the looks, especially mine.

[cricman]

Ach, du Liebe!!!!!

The primary thing that got me initially interested in the R1150R was the aesthetic of those 2 beautiful cylinders, jutting out from the crankcase! I saw one at the Cycle World motorcycle show, and it was added to my short list of motorcycles to consider for purchase. I had been comparing several bikes, and I hadn't even considered a BMW. One look at the Silver RR, and it was added to the list. After intensive research (including this board) and the great interest rate BMW was offering, I ended up with one of the best looking bikes ever made, opposed cylinders and all!!!!!

cricman

[geothepencil]

As much as we love our R/Rs', check out the new R1200S sometime. It may be the ultimate presentation of the boxer engine. It looks like an airplane with wheels or alternatively a very striking motor with the most minimal of necessities attached to it.

geo

[CycleRob]

hep303, In answering all your questions . . . . .

The Boxer engine isn't used a lot because it is expensive to produce, like a V-Twin with seperate heads, cam drives, valve covers, etc - - - - it's too wide and heavy compared to a parallel twin and it has an undesireable torque reaction. It's front-to-back crankshaft orientation lends itself to shaft drive, which is also more expensive, heavy and uncommon while shaft drive is still not considered to be in the high performance family. The BoxerTwin exhaust note also has a common industrial engine, aircraft drone or at best a small muffled sportscar tone. It's 80 year old engine design implies a primitive sloth with low performance. A non BMW boxer twin may also be seen as a copycat immitation and therefore undesireable, unless it offered very high performance..

--BUT--

A Boxer engine is very easy to service, has superior cooling efficiency, very low vibration and a record low center of gravity. With a low parasitic drag characteristic of a dry clutch and common axis, gear driven primary input, transmission and drive shafts the powertrain losses are minimal. The engine, with it's overdrive gearing, seems to be designed for efficient, reliable, high speed touring with a longer than usual 6,000 mile engine oil drain interval allowed by it's engine-only oil supply..It's high fuel efficiency capability follows the designed in power curve assigned by the manufacturer within the known capabilities of it's in-head camshaft, pushrod and rockerarm valvetrain with air/oil cooling. It's quirks have annoyed, bored or repelled the masses while endearing them to loyal folowers, who, for the most part have tried many other engine types and chosen the BoxerTwin as the best for the pleasant way it works so well at whatever they want to do on two wheels.
.

[DJ Downunder]

I wonder when BMW will release this.

DJ

[awagnon]

I agree with CycleRob. What I like is the ease of service. I can adjust the valves on my R1150R in 30-45 minutes, total. Try to do that with a V-twin or parallel twin. OTOH, maybe they need adjusting more often? I don't mind.

[yjleesvrr]

I agree with eveything except two things:

1) Most BMWs overall feel like they have a higher center of gravity because most BMWs are tall bikes. My '02 R certainly feels more top heavy than my SV650. And despite my Roadster weighing nearly 100 lbs. lighter than my Dyna Super Glide Sport, my Harley definitely is a lot easier to maneuver around in a parking lot because the bike as a whole is lower to the ground.

2) I actually love the look of the boxer heads ticking out into the wind. I notice the beauty of this on other BMWs going down the highway, as well as when I glance down at my Roadster's engine when I'm on the road. Functional sometimes is beautiful.

I liken the R259 boxer as sort of a diesel engine in terms of performance. It doesn't rev as high, but it provides lots of torque down low, has longevity, and durability beyond most other motorcycle engine designs.

[GJBushman]

I own an R1150R and a K1200RS. My wife rides the Roadster and I ride the K12. I had put 30K+ on boxers before riding the K12. I like the K bike better. It suits my riding more. Once you've had the smooth power of a K bike, its difficult to go back. However, I would like to try the new R1200R. I like the idea of more hp on a boxer.

[celticus]

Jamie , I just went from a k1200RS to an R1200R and I love the new bike. It's just lighter and more manuverable.
I guess you like what you like.
I love your avatar by the way.
Mark

[GJBushman]

Mark,

Yes, the K12 is a heavy bike. And I bet I would appreciate the nimbleness of the R12R. I love the K12 at speed, steady as a rock. Wind protection with the GT screen is also great. One thing I never liked about the Roadster was the lack of a decent windshield. It's a naked bike for sure. And yes, I'm a big Zappa fan.

[wncbmw]

There is nothing like a twin and the two jugs sticking out is forever embedded in my mind as the sign of a durable, long running machine. Beauty is in the eye of the beholder and for this eye . . . well, I love the BMW twins!

If for some reason, they all disappeared, that Italian v-twin would be a suitable substitute!

[JCsman]

It may be my age. But I think the boxer and a British single typify how a "motorcycle" should look.

But I sure don't want a 1960's British thumper as my only bike

(When my wife isn't around and I revert to my Neanderthal ways) I tell folks my bike has long legs, big jugs and full hips (system cases, doncha know).

Now what could look better than that?

[peterbulgar]

Back in the day of air-cooled parallel twins and V-twins, the boxer was a superior design. Even in the early days of air-cooled inline fours the boxer had some advantages as long as the rider didn't care about maximum power. However, to keep up in the marketplace BMW had to increase the size and power of the engine to the point where vibration became a problem. So along with four valve heads and twin-spark ignition we now have a counterbalancer - so much for the simplicity of a twin. It is also getting more and more difficult to meet emissions requirements with an air-cooled engine, but I don't know if BMW twin buyers would react favorably to a water-cooled boxer. I suspect that it costs BMW about the same to produce the boxer as it does to make their four, and that BMW would gladly retire the boxer if they weren't worried that that they would lose half their customers.

So, we are left with a design that has had to give up some of its former advantages in order to keep up with the times, and which is still out-powered by fours of much smaller displacement, and even some twins of equal or smaller size. Even the advantatges of shaft drive are becoming suspect given the numerous reports of various rear end failures on newer BMWs - I'd rather replace a belt every 25k miles than a crown bearing. I wouldn't have anything else, but I'm glad that I don't feel obliged to justify my choice with practical arguments.
Peter '73 R75/5, '04 R1150RA