Topic: What are the advantages of the BMW "/5" series bikes?

[DH]

I won't pass judgement on something I've only ridden once, so I'm ignorant when it comes to BMWs for the most part.
I rode a /5 bike, can't remember what size for a short distance. Not far enough to really learn anything except that
when the throttle is "blipped" the bike rocks to one side, and my sohc 750 is much smoother.. What is it that owners like about these, and how are they better or inferior to an sohc 750? Again, not passing judgement, just curious. I've only heard good things about them.

[George_s]

^^^ What he said! ^^^

[simon#42]

i love my 75/5 it has  330,000 on the clock now and is still going strong . the 5's are a bit smoother than the latter 6's and 7's as they have a heavier flywheel .
on the negative side they are a bit slower and the gear change is worse . for big trips i now use my 7 series st  . as you said they are a bit different to other
bikes and you do have to spend a bit of time getting used to them .
not better or worse than a sohc honda just different . thats why i have both .

[SOHC4 Cafe Racer Fan]

You can ride the BMW twin forever.  The /5 series are not speedy, and the shifting is clunky, but they are pretty reliable and cool.

My buddy's R50/5 that I keep in running order while he's out of the country:

[BomberMann650]

I sure can't afford to play ball with the beemer club in town.

But I can still outrun them 

Though the one man's experience on his BMW r69 does show in the corners.  He charges in every time.  Even with the crazy fork design and drum brakes.  40 years no fear.

[simon#42]

just to pick cal up on one small point , the 2 series is a totally different engine  [ the cam is above the cylinders not below ]

[Bankerdanny]

The torquing is caused by the horizontally opposed engine, not the shaft drive.

[DH]

Are these similar in design to the modern cruiser engines honda uses? Just not liquid cooled? Any design advantage for
longevity over other designs? I'd never thought they'd go that far.

[BomberMann650]

Are these similar in design to the modern cruiser engines honda uses? Just not liquid cooled? Any design advantage for
longevity over other designs? I'd never thought they'd go that far.

I suppose it would diversity the direction that force gets applied to the crankshaft.  May aid in balancing and smoothing the running motor.

[Scott S]

 I recently put a. R100/7 back on the road. It's very different from the SOHC4, some of the engineering seems to have been done "just because we can" or over biers, and it can seem.... agricultural.
 It doesn't excel at anything, BUT.....it does everything well. It's comfortable, smooth, deceptively fast and handles better than you think it is doing at the time. I'd say the brakes are a weak spot, especially the rear disc. Mine is dual plugged and gets 47 mpg.

 I knew nothing about them before, but I can understand the appeal now.

[Scott S]

 Oh, and the gearbox is indeed clunky.

[BomberMann650]

Oh, and the gearbox is indeed clunky.

I'm curious to know why the main case of the engine is so large in proportion to the cylinders?

[simon#42]

well there is an alternator stuck on the front and a bloody great big starter motor on the top .

[BomberMann650]

well there is an alternator stuck on the front and a bloody great big starter motor on the top .

Ahh, so thats what lives under all those covers!

[theslayedsaint]

Because they are badass and feel like your on a motorcycle truck

[Bankerdanny]

It's true the crank generates the torque in the direction of it spins, but other flat opposed engines don't suffer the same "twist" if you will. A Porsche motor for instance is vastly different in how it reacts within the frame.


Their Paralever equipped twins don't have the same sensation despite being shaft driven and flat opposed. So managing it, or design the suspension around it has become their solution I guess.

Every BMW I've ever owned or ridden, has always had that "lurch" (my word) and many of them were K motors. I've always liked it actually, sort of reminds me of riding a Quarter Horse. My current K is more subtle. Most it lurches forward (very quickly). 

The R90 I'm rebuilding (ruining the purists would say) has a much lightened crank and flywheel for shifting and revving improvements. Still the wonderful old air head.

Right, but the Goldwing engine and the Porsche/VW/Subaru engines are a 4's or 6's, so you have pistons going out on both sides of the engine at the same time to cancel each other out, which the BMW and Motoguzzi twins don't.

[DH]

I'm curious to know why the main case of the engine is so large in proportion to the cylinders?

As well there's an airbox on the top, at the rear.

Empty cases for an R90

I've always wondered why this design looks like it does. Excellent...I've admittantly had little experience working on anything else
other than Hondas, so I appreciate the information. It helps to open up the mind a bit.

[333]

Torque lash does occur on virtually all shaft drive bikes. Some better than others.  It's not the type of motor that does it. It's the 90 degree turn the power takes at the wheel.  Gold Wings do it. Cars do it, but you don't see or feel it as much because cars HAVE 4 WHEELS. Stop comparing cars to bikes.  Torque lash in cars is clearly evident at the drag strip.

There is also power loss with shaft driven bikes. Any time you take a 90 degree turn of power you lose power.

[simon#42]

It's true the crank generates the torque in the direction of it spins, but other flat opposed engines don't suffer the same "twist" if you will. A Porsche motor for instance is vastly different in how it reacts within the frame.


Their Paralever equipped twins don't have the same sensation despite being shaft driven and flat opposed. So managing it, or design the suspension around it has become their solution I guess.

Every BMW I've ever owned or ridden, has always had that "lurch" (my word) and many of them were K motors. I've always liked it actually, sort of reminds me of riding a Quarter Horse. My current K is more subtle. Most it lurches forward (very quickly). 

The R90 I'm rebuilding (ruining the purists would say) has a much lightened crank and flywheel for shifting and revving improvements. Still the wonderful old air head.

Right, but the Goldwing engine and the Porsche/VW/Subaru engines are a 4's or 6's, so you have pistons going out on both sides of the engine at the same time to cancel each other out, which the BMW and Motoguzzi twins don't.

the bmw pistons go out at the same time and in theory cancel each other out , as they are slightly offset this is not perfect
the reason for the bike moves to one side when the throttle is bliped is the crank runs front to back of the engine,  there is also a heavy flywheel and a clutch to add to the gyroscopic effect 
it has nothing to do with the shaft drive and is not an issue when moving . the shaft drive does however cause the rear of the bike to rise under acceleration thats why the later bikes have
an extra joint in them [ paraleaver ]