Author Topic: New 850 BMW with 95HP, 270 Crank !  (Read 2784 times)

Offline leafman60

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« Last Edit: November 07, 2017, 07:55:22 AM by leafman60 »

Offline arveno

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Re: New 850 BMW with 95HP, 270 Crank !
« Reply #1 on: November 07, 2017, 11:20:13 AM »
Bella!!!
And finally a 21 inches  front wheel !!!

BMW gets it...

Piaggio? Not so much.....



Online PeteS

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Re: New 850 BMW with 95HP, 270 Crank !
« Reply #2 on: November 07, 2017, 12:49:30 PM »
My 800 Triumph 800 XC is lighter than both of them. Triumph is supposed to announce their new 800s soon. Should be interesting.

Pete

Offline Kiwi_Roy

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Re: New 850 BMW with 95HP, 270 Crank !
« Reply #3 on: November 07, 2017, 01:03:46 PM »
Are we supposed to get exited Haha, I have that already without a lot of extra junk whirring around.

•Extremely powerful and emotional sound, produced by a crankshaft journal offset of 90 degrees and firing interval of 270/450 degrees.
« Last Edit: November 07, 2017, 01:05:59 PM by Kiwi_Roy »
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Offline Tusayan

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Re: New 850 BMW with 95HP, 270 Crank !
« Reply #4 on: November 07, 2017, 01:13:23 PM »
Are we supposed to get exited Haha, I have that already without a lot of extra junk whirring around.

Extremely powerful and emotional sound, produced by a crankshaft journal offset of 90 degrees and firing interval of 270/450 degrees.

Yep.  Giulio Carcano, Fabio Taglioni and any number of industrial engine manufacturers figured out a long time ago that a 90 degree V-twin gets the job done without a lot of extra hardware like counter-balancers, multi-throw crankshafts and water cooling.   Now its become fashionable to make a parallel twin perform and sound like a 90 degree V-twin by adding lotso f stuff, and I think the only benefit is a slightly more compact and possibly cheaper to produce engine... with lots of hardware  that wouldn't otherwise be necessary.

Online PeteS

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Re: New 850 BMW with 95HP, 270 Crank !
« Reply #5 on: November 07, 2017, 01:54:54 PM »
Not sure about the extra hardware part. A good friend here took is late '60s Triumph twin and moved the crank 90 degrees. Megacycle ground him a new cam and he was pretty much set. Rode it cross country a number of times.

Pete

Offline Tusayan

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Re: New 850 BMW with 95HP, 270 Crank !
« Reply #6 on: November 07, 2017, 02:17:15 PM »
Not sure about the extra hardware part. A good friend here took is late '60s Triumph twin and moved the crank 90 degrees. Megacycle ground him a new cam and he was pretty much set. Rode it cross country a number of times.

Pete

A late 60's Triumph with a 270 crank is smoother than stock, but I don't think many would say it's smooth enough for sale as a 2017 model.  In order for a 270 degree crank vertical twin to be relatively vibration free, you still need a balance shaft but it is a less problematic design because the forces are less than with a 360 crank. 

The Royal Enfield 650 twin website has a photo of their 270 crankshaft and balance shaft setup: https://royalenfield.com/motorcycles/twins/images/engin_inner.jpg

The F800 BMW with its 360 crank has giant bob weights under the crankshaft with an extra con-rod just to drive the bob-weights: http://www.ashonbikes.com/sites/default/files/images/BMW_F800_balance_5.jpg

Meanwhile a 90 degree V-twin achieves the same balance with just a single throw crankshaft and no extra balance hardware.
« Last Edit: November 07, 2017, 02:51:31 PM by Tusayan »

Offline kingoffleece

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Re: New 850 BMW with 95HP, 270 Crank !
« Reply #7 on: November 08, 2017, 03:00:16 PM »
The BMW version of the Africa Twin?
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Re: New 850 BMW with 95HP, 270 Crank !
« Reply #8 on: November 08, 2017, 04:31:53 PM »
Not sure about the extra hardware part. A good friend here took is late '60s Triumph twin and moved the crank 90 degrees. Megacycle ground him a new cam and he was pretty much set. Rode it cross country a number of times.

Pete

  Dick Harris?  I have met him and his cross country 70 Triumph 650  90 degree..

Offline garbln

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Re: New 850 BMW with 95HP, 270 Crank !
« Reply #9 on: November 08, 2017, 04:48:40 PM »
Ben doing that for years on old XS650 Yamaha's.  No counter balencer tho.  Some say it's worth the trouble, some say not.  Whatever.

Online PeteS

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Re: New 850 BMW with 95HP, 270 Crank !
« Reply #10 on: November 08, 2017, 05:07:58 PM »
  Dick Harris?  I have met him and his cross country 70 Triumph 650  90 degree..

Rough, yes it is Dick. Last time I saw him and the bike was at the Norton Polar Bear ride a year ago.
Great guy.

Pete


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