Boxer Engine Is it the perfect motorcycle engine?

[yjleesvrr]

And of course once you have a liquid-cooled boxer engine you might as well not have the boxer configuration since you don't need to stick the heads out to cool them anymore.

I have to admit one of the appealing things about BMW R bikes is the boxer engine. The heritage and durability of the fundamental design is proven. I'd even attribute character to boxers as well. Perhaps not quite to the extent v-twins have, but fairly close. In top gear, my R1150R is incredibly smooth between 55 - 70 mph and emits a nice sound. It gets slightly vibey from 75-90 mph, but then smooths out again beyond that.

I think BMW will keep the boxer engine for a while and fiddle with computers and catalytic converters to maintain compliance.

[riceburner]

One issue with the Boxer that no-one has yet mentioned is "Ground Clearance".

at extreme cornering (which is VERY possible with BMWs) the cylinder head WILL ground out and lift the front.

[geothepencil]

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.

The K has a taste for speed and feats of distance and the R is generally a big happy puppy also capable of distance as I see it. Round out your garage with a V-Max and you will have it all !

geo

[hep303]

Some excellent insights from everybody. Hey DJ what is that engine you posted?

With regard to the aesthetics of the boxer, my untrained eye when I first saw it was that it looked awkward. People unfamiliar with it ask me questions when they see it. "Why is it sticking out like that?" "That's a funny looking engine" I get the impression that novices don't find it pretty, however it has grown on me. Understanding the engineering has influenced my attitude about the looks. You have to admit though that a V-Twin follows the lines of a traditional frame better than a boxer. In my book, form does not follow function. Function is all I need. Another question for the really experienced folks here: If you took a boxer and V-Twin of equal size and displacement and rode them and maintained them exactly the same, would you expect to get significant longer life out of the boxer? Would there be higher maintenace costs for either?

[hirsty]

I almost fell into Boxer ownership by accident, and now I'm such a convert I don't think I'll ever be able to buy anything else.

Having test ridden one recently, I too give a vote for the R1200S being the (so far) ultimate incarnation. Bonuses allowing next year, and subject to the hard cases being released, it will be mine ...

[geothepencil]

No, the perfect engine is/was the 3 cylinder K75 motor. Witness the 300K mile examples still on the road. More power/different gearings would have helped its longevity in the market, but the counterbalanced little K motor itself is just fabulous. Some would object to a lack of "character", but at 60 mph, there is no sensation of a motor running under you at all. Sometimes that is a nice change. I always take mine out when I want a bike to accompany me down a country road rather than the other way around.

geo

[JCsman]

No, the perfect engine is/was the 3 cylinder K75 motor. Witness the 300K mile examples still on the road.

The K75 didn't apeal to me, but you have a point about the motor. A triple has real advantages. Odd then (or isn't it) that when BMW looked at the middle size market, they went with a parallel twin in 800cc rather than 3/4 of the K1200 at 900cc.

Yes, the twin is narrower, but a three has better inherent balance and all that engineering time on the 1200 cc surely would have been of use.

[johno]

I am on my 4th oil head Boxer, and it wont be my last.
I like the odd looks, the torque, the general overall feel of the engine,
and the bike.
The ground clearance of the heads wont be an issue to me, as I am no Valentino Rossi.
I find the Boxer easier to ride that conventional V twins. Not so much snatching at lower revs.
Generally one of the finest engines out there.

[Sunbeemer]

Never having owned a fore and aft crankshaft bike before this, I was surprised at how little effort is required to flick the bike in turns. I suspect that this is due to the lack of side-to-side gyroscopic stabilization (as compared to a sideways mounted crankshaft), as well as the motor's low center of gravity. The torque reaction of the Boxer's longitudinal crankshaft is only noticeable (to me) with sudden bursts of power at low speeds, before the wheels' gyroscopic stabilization becomes significant. Balance at low speeds is enhanced by the wideness and lowness of the cylinders (saggy jugs ), so IMHO, it's about as good as it gets!

I wonder how the in-line Valkerie rides? But...I wouldn't want to work on one, and sure wouldn't want to have to pick one up!

[joejeweler]

A few obvervations from someone who has owned a 1970's era Honda CB 350, an early Suzuki GT380 3 cylinder 2 stoke, THREE 1979 Honda dual purpose XL500S single cylinder thumpers, (still have a beat up version of the XL500S that i got that way),.......

............ and currently ride a super nice 1982 Suzuki GS850GL 4 cylinder "Cruiser" with Vetter fairing and luggage trunk, (Super low seat a nice bonus)..............

.........when i'm not riding my 2004 R1150R with city cases and Parabellum touring windshield and new Corbin one piece leather seat.

I love the low end grunt of the boxer and distintive looks, but the overall height of the boxer just seems unnecessary to me. I'm 5'10' with a 30" inseam,.......and i don't like to have to be on tiptoes if i want BOTH feet parked on the ground at once or when backing out of a garage.

Seems to me with the height of the cylinders not being a factor,......these bikes "should" be one of the lowest around for the rider. The width of the seat is also a bit extreme,......and the frame width limits the amount any seat can be made to fit in tighter so my thighs don't get pushed out. I took off the side strip panels and this helped a bit,.......but still uncomfortably wide at times.

I think these are designed "high" to get the ground clearence up for those wanting to corner at high speed. But i'm not one of those, and would give up a few inches of ground clearence to get my feet on the ground.

........battery under the gas tank was not a smart move, IMO......hard to reach and a pain in the A$$ to service or replace. It looks like there was plenty of room under the seat had some other things been better placed. The battery under the gas tank also forces it up, and if i designed as high a gas tank it would be because it was holding 8 or 9 gallons of fuel for long rides,.....NOT because it had to be because i stuck a battery under it.

One thing that makes me a "little" nervous is having an electric fuel pump "in" the fuel tank. Don't know if any of these have ever had a short that caused a spark to fly,.......'because i sure as hell wouldn't want to be the first this happened to! Seems to me an outboard pump would be safer and work just as well.

Before this ends up sounding too much like a BMW negative review,..bear in mind that most times i ride the BMW,.....although i think i'm not a perfect body type for the boxer. I sure wonder how some of the ladies drive these with even shorter legs and dealing with the fairly heavy weight.

The BMW is still fun for me to ride,.......in spite of it's problems for me. It cruises steady and with the 6th gear (mine has the super high 6th) the revs and vibration are low. The heated handgrips and clock are nice additions none of my other bikes had. First bike also with fuel injection,......and it's nice to have a steady idle even when cold. (carbs not even close).

The brakes are GREAT, and mine are the non-ABS. Anti-dive characteristics are one of the bikes best features,.......something i don't think i can live without now that i've had it.

Some things i'd give up to get the seat lower and more narrow. Bring the engine down to 750cc or 850cc if it got the seat lower and narrower. Gas milage would go up as a side bonus,......and a smaller gas tank could be used to offer the same range..........

........and get the battery under the seat where it belongs for easy servicing!

[riceburner]

If you took a boxer and V-Twin of equal size and displacement and rode them and maintained them exactly the same, would you expect to get significant longer life out of the boxer? Would there be higher maintenace costs for either?

Depends on whether or not they were designed by the same person/team, built by the same technicians/factory, with the same materials and to the same standards.




FWIW - IF all the above were true (and I know of no manufacturer that produces/produced an L-twin AND a boxer) I'd say the L-twin was probably better equipped in the longevity stakes: an L-twin (dependant on timing obviously) has both primary AND secondary balancing moments - whereas a Boxer engine only has primary balance. I think I'm correct in saying that the L-twin would be less abusive (if only by a fraction) to it's internal bearings.

[wncbmw]

grothepencil said:

No, the perfect engine is/was the 3 cylinder K75 motor

Back in the day, when the family was young and I was riding my old RS forever because I couldn't afford anything else, I refused to ride a K75 because I thought I would be unable to resist it. The K100 was too buzzy for me but all the people who rode the K75 raved about it. Years later, I bought a used one between the 1100 GS and the Roadster and although the motor was indeed slick as eel snot, coming from the GS, the suspension left a lot to be desired. Sweet bike though and if I had wanted to put some money in Ohlins for it, no doubt it would have been wonderful.

Of course, the clutch splines giving up the ghost on a ride, yielding my only ride home towing my bike, took some of the luster off.

But the siren song of the twins, specifically the 1150R, was too strong.

There are BMW fans who insist the R75/5 was the peak of BMW design. And there is another group that insist the K75 was it! They both have good points!

[JCsman]

Anti-dive characteristics are one of the bikes best features,.......something i don't think i can live without now that i've had it.

Amen, Joejewler. The first few times I pulled firmly on the lever were a revelation. But, I'm afraid I'm spoiled.

I've given some thought to a KLR 650 as a second bike. But I get the willies thinking about the transition to (relatively) weak, non-ABS brakes and the hobby horse feel with that long-travel suspension after a few years on the Roadster.

[challey]

joejeweler said:

Seems to me with the height of the cylinders not being a factor,......these bikes "should" be one of the lowest around for the rider. The width of the seat is also a bit extreme,......

As someone with a very short inseam (29"), I say "Amen" to the above, though frankly it's my only real gripe.

While I did not have this issue with my vertical twin (Triumph Bonneville) or either of my V-twins (MG V7 and Ducati Darmah), none of those had the combination of handling, comfort, torque and braking that the R does.

The point however is, only one of these positive traits is related to the Boxer design.

[1150929]

Great post, and I agree with most points, except I think the boxer is so ugly it's beautiful!

Best motorcycle engine? Not for a sportbike, as much as I love the new 1200S. Nor a dirtbike. But maybe the best configuration for a standard or a tourer.

I love rotary engines, get 250hp from my normally aspirated 1.3L RX8. Basically, three moving parts, and smoother than anything else. Some bikes used to have them, but manufacturers since abandoned it in favour of lower cost and less R&D. But best potential bike engine IMO.

[yjleesvrr]

Can anyone name an engine that looks pretty?

[peterbulgar]

Can anyone name an engine that looks pretty?

Well, beauty is in the eye of the beholder, but here are my picks for the most attractive motorcycle engines:
1) Vincent Black Shadow
2) Ducati Diana Mk III 250cc single
3) Ducati "round case" 750cc twin
4) 1939 Harley 61" "Knucklehead"
5) 1967 (with finned rocker covers) BSA Thunderbolt

"Pretty" might not be the right descriptor, but in all the above engines you get the idea that there was one designer who gave a lot of thought to how the various parts would work together to make one unified and well-proportioned design. Actually, just about any air-cooled, small displacement Italian single from the 50's or 60's has the same quality of design integrity. IMHO, YMMV.

If you want to call an engine "handsome" I would add the Royal Enfield 750cc twin and the BMW /5 series - both designs have a chunky and purposeful look that is uncluttered but still mechanical. For that matter I've had strangers comment on how nice my R looks, although I think that it looks a bit ungainly.

If you ever get a chance to examine a Bugatti from the 20's or 30's (a Type 35 for example) be sure to take a close look at the engine - it is truly a work of art. Ettore Bugatti seems to have given as much thought to the engine as sculpture as he did to its mechanical function, although to be sure his engines were very successful designs.
Peter '73 R75/5, '04 R1150RA

[hep303]

Hey joejeweler,

I am similar in stature to you and I also have the Corbin seat. I switched back to the original though. The Corbin seat raises you up about an inch and it is a little wider. The Corbin does provide more comfort for long hauls. I mostly make shorter trips so I don't mind.
You will be a little closer to the ground if you use the OEM seat.

[riceburner]

Great post, and I agree with most points, except I think the boxer is so ugly it's beautiful!

Best motorcycle engine? Not for a sportbike, as much as I love the new 1200S. Nor a dirtbike. But maybe the best configuration for a standard or a tourer.

I love rotary engines, get 250hp from my normally aspirated 1.3L RX8. Basically, three moving parts, and smoother than anything else. Some bikes used to have them, but manufacturers since abandoned it in favour of lower cost and less R&D. But best potential bike engine IMO.

Norton were using Wankels less than 10 years ago.

Problems they had were less (read NO) engine braking, so brakes cooked themselves very quickly during races, and the engines got VERY hot.

Fantastic bikes though.

[JCsman]

Can anyone name an engine that looks pretty?

Well, beauty is in the eye of the beholder, but here are my picks for the most attractive motorcycle engines:
1) Vincent Black Shadow
2) Ducati Diana Mk III 250cc single
3) Ducati "round case" 750cc twin
4) 1939 Harley 61" "Knucklehead"
5) 1967 (with finned rocker covers) BSA Thunderbolt

There is real beauty in some of the (especially older) engines. Let me throw in the Ariel Square Four.

Your first on the list reminded me. There is an artist named Daniel Peirce (yeah "e before I" is correct) that has a series of beautiful photos of motorcycle engines. Including, of course, the Black Shadow. It might be worth while to "google" his name and take a look - if that doesn't work I can try to post a link. I liked them so much they went on my "hint" list for Christmas (and, no I am NOT Daniel Peirce, nor do I play him on TV).

Link added. But the samples on his site don't do the real ones justice.

http://www.trickphotog.com/engine_project.htm