BMW R1200RT/R1250RT Forum

Posted: **Thu Mar 15, 2018 10:41 am**

Omobono wrote: Am I wrong of at least some of the RnineT series (the scrambler?) have a different firing order?

They are twins. How can they have a different firing order?

Posted: **Thu Mar 15, 2018 11:13 am**

The firing order is 1-2 or 2-1 may be worth checking with a dealer  :silence:

Posted: **Thu Mar 15, 2018 11:54 am**

Pickaxe wrote: They are twins. How can they have a different firing order?

I think he means firing timing. This can be achieved by offseting the crank pin journals wrt each other.

Posted: **Thu Mar 15, 2018 12:53 pm**

How, on a flat (horizontal) twin, can the crankshaft be anything other than 180deg offset.

When sat on the bike, No. 1 cylinder is LHS, No. 2 cylinder is RHS.

Posted: **Thu Mar 15, 2018 1:53 pm**

Yes I meant that. For example making the engine fire 270-90 like, I think, Triumph did with their twins. I seem to have read somewhere at least the scrambler of the RnineT series has this and it sounds better.

I have found this concerning Triumph

"The parallel twin is currently used by BMW, Triumph, Yamaha and Kawasaki. The BMW F800s use a 360 degree firing order to give great torque figures although the revs are limited to 9000rpm because of the vibes. Yamaha and Triumph have both used a 270 degree firing order. A 270-degree crank imitates the sound and feel of a 90º V-twin, and there are other advantages. In contrast to the 360 and 180 parallel twins, the 270 crank gives a compromise that allows a more regular firing pattern than a 180-crank, and less vibration than a 360-crank. This "big bang" concept was used on the 209 Yamaha R1, and Triumph’s Thunderbird 1600 has a 270 degree crank too."

https://www.motorcyclenews.com/new-ride ... lel-twins/

Posted: **Thu Mar 15, 2018 1:59 pm**

Omobono wrote: Yes I meant that. For example making the engine fire 270 degree firing order like, I think, Triumph did with their twins. I seem to have read somewhere at least the scrambler of the RnineT series has this and it sounds better.

EDIT: I have found this concerning Triumph
"The parallel twin is currently used by BMW, Triumph, Yamaha and Kawasaki. The BMW F800s use a 360 degree firing order to give great torque figures although the revs are limited to 9000rpm because of the vibes. Yamaha and Triumph have both used a 270 degree firing order. A 270-degree crank imitates the sound and feel of a 90º V-twin, and there are other advantages. In contrast to the 360 and 180 parallel twins, the 270 crank gives a compromise that allows a more regular firing pattern than a 180-crank, and less vibration than a 360-crank. This "big bang" concept was used on the 209 Yamaha R1, and Triumph’s Thunderbird 1600 has a 270 degree crank too."
https://www.motorcyclenews.com/new-ride ... lel-twins/

Posted: **Thu Mar 15, 2018 2:24 pm**

BMW R nine T Scrambler

The Bird might be a parallel twin, but the Bike is definitely a boxer (opposed) twin.

Posted: **Thu Mar 15, 2018 3:14 pm**

Like the bird! ^-^
But it would be possible to do the same thing with the boxer, right? That is, having the cylinders fire in such an order that the boxer twin sounds more like a V twin?
Honestly, much as I like my present bike, if BMW made a Tourer with such an engine I would run to buy it and never sell it again... 

Posted: **Thu Mar 15, 2018 3:23 pm**

David. wrote: How, on a flat (horizontal) twin, can the crankshaft be anything other than 180deg offset.

When sat on the bike, No. 1 cylinder is LHS, No. 2 cylinder is RHS.

Because the crank pins on the crankshaft be be at any angle to each other. At present they are displaced by 180 degrees wrt the main bearings. However it is mechanically possible to build them at any angle between zero and 180. The reality would then be balance shafts etc.

Posted: **Thu Mar 15, 2018 3:49 pm**

bandytales wrote: Because the crank pins on the crankshaft be be at any angle to each other. At present they are displaced by 180 degrees wrt the main bearings. However it is mechanically possible to build them at any angle between zero and 180. The reality would then be balance shafts etc.

+1. As you say, having the crank-pins at anything other than 180 degrees would destroy the primary balance of the engine (pistons go in and out together) and render the boxer engine pointless.

Maybe Mr. Omobono (Tenni) should stick to Guzzi's (great bikes, I hear)

Posted: **Thu Mar 15, 2018 4:05 pm**

Omobono wrote: Like the bird! ^-^
But it would be possible to do the same thing with the boxer, right? That is, having the cylinders fire in such an order that the boxer twin sounds more like a V twin?
Honestly, much as I like my present bike, if BMW made a Tourer with such an engine I would run to buy it and never sell it again...

It would be like riding a cement mixer......  As mentioned above, it's all about primary balance.  Mind you, riding like a cement mixer would continue the theme of chucking a brick in one as you engage first gear.

Posted: **Mon Mar 26, 2018 3:33 am**

David. wrote: BMW R nine T Scrambler

Re: 20019 RT

You mentioned a BMW R 9? Where is it? I don't see any bike

Posted: **Thu Mar 29, 2018 1:41 am**

gogs01 wrote: I'm not looking for more power, more weight or a higher price - all of which are likely to appear on a 2019 R1250RT.
Improved fuel economy, lower emissions and integrating the GPS would be interesting though ..... ;D

I'm with you... when it comes to power, my '14 R1200rtw has plenty of it.  It's quick, reliable, fun, and it looks great.  Fuel economy is great at 50+mpg.  Surely less emissions than my old Suzuki 185.  I'm happy with the GPS, but not thrilled.  I wouldn't want it integrated though.  Unless BMW could guarantee that software and interface upgrades would be provided.  My '12 Toyota PU has an integrated system and there hasn't been an upgrade since it was in the showroom.  Damn near runs on ASCII.