Author Topic: Is a sustained 7,000 RPM too much? How about 8,ooo?  (Read 9571 times)

Offline The Mighty Gryphon

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Re: Is a sustained 7,000 RPM too much? How about 8,ooo?
« Reply #50 on: November 29, 2019, 09:47:30 PM »
Not maybe. In the description under the video at YouTube, the contributor indicates that it's a 1990 4V.

The bike in the video has a four valve instrument cluster.  See the lines visible on the face of the speedo.  Very possible the actual speed was about 5% lower than shown. 

Still, the ease at accelerating is pretty impressive.   I know from my K100 4V that these bikes have an eagerness to go faster without being alarming which is the result of a wide powerband and lots of torque.

As far as opening up, I have to be careful around here when going 100+.  Law enforcement has been known to seize vehicles.
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '91K100RS White/Blue, '89 K100RS Special edition White/Blue
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'91 K100RS "Moby Brick Too
'89 K100RS SE
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Offline billday

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Re: Is a sustained 7,000 RPM too much? How about 8,ooo?
« Reply #51 on: November 30, 2019, 07:21:50 AM »
I also noticed the ppl moving over for him to overtake. That was my favorite thing about driving in Germany. Felt so much safer than here, even though the speeds were so much higher.

My dad was over there right after WW2. He said you'd get two trucks running side by side for miles in a slo-mo drag race while traffic piled up behind them.
  • New York State, USA 10977
  • 1985 K100

Offline The Mighty Gryphon

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Re: Is a sustained 7,000 RPM too much? How about 8,ooo?
« Reply #52 on: November 30, 2019, 08:09:07 AM »
The trucks still do that here with their damn speed governors.  It can take an entire morning for a truck with a governor set at 65.0000001mph to pass another one with the governor set to 65mph.  Of course the asshole driving the slower truck will never back off for 10 seconds to let the "faster" truck pass him.
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '91K100RS White/Blue, '89 K100RS Special edition White/Blue
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'91 K100RS "Moby Brick Too
'89 K100RS SE

Offline Nine80seven

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Re: Is a sustained 7,000 RPM too much? How about 8,ooo?
« Reply #53 on: November 30, 2019, 10:02:47 AM »
What's the rear gear on that bike?  2.75?  If an old KRS with 2.81 tops out at 137 give or take, that four valve must have one less notch.  30/11? 
  • MN
  • 85 K100RS

Offline Laitch

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Re: Is a sustained 7,000 RPM too much? How about 8,ooo?
« Reply #54 on: November 30, 2019, 10:15:53 AM »
If an old KRS with 2.81 tops out at 137 give or take, that four valve must have one less notch.  30/11?
According to the K1/K100RS 4V rider's handbook, the K100RS is 31:11.
  • Along the Ridley in Vermont.
  • 1995 K75 72,000 miles
I wept because I had no radials until I met a man who had no splines.
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Offline Nine80seven

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Re: Is a sustained 7,000 RPM too much? How about 8,ooo?
« Reply #55 on: November 30, 2019, 11:16:16 AM »
If it had a 31/11, 2.81, then it'd have to turn a lot more than 8500rpm to get to 150mph. 
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Offline Laitch

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Re: Is a sustained 7,000 RPM too much? How about 8,ooo?
« Reply #56 on: November 30, 2019, 12:09:46 PM »
If it had a 31/11, 2.81, then it'd have to turn a lot more than 8500rpm to get to 150mph.
I'm just the messenger.

What does a lot mean? What would the difference in mph amount to at 5000rpm?
  • Along the Ridley in Vermont.
  • 1995 K75 72,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline Nine80seven

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Re: Is a sustained 7,000 RPM too much? How about 8,ooo?
« Reply #57 on: November 30, 2019, 02:49:09 PM »
I guess the vid shows a little over 9K rpm which would be about 7-8 hunnerd more rpm, which would be enough for about 12 mph, which would be 150 thereabouts, with a 2.81 rear gear.  All things being equal, tire circumference etc., 2.81 will yield about 16.1 mph per thousand rpm.  Unless I'm losing my mind.  Four valve having ten more ponies. 

It's snowing, sleeting, raining, slop outside.  Fun.  No riding today.  Turkey hash for supper. 
  • MN
  • 85 K100RS

Offline Laitch

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Re: Is a sustained 7,000 RPM too much? How about 8,ooo?
« Reply #58 on: November 30, 2019, 04:57:15 PM »
Unless I'm losing my mind.
It could just be the effect of turkey- and potato-generated endorphin affecting perception. :-) That should pass away along with the leftovers.
  • Along the Ridley in Vermont.
  • 1995 K75 72,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline cycleman

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Re: Is a sustained 7,000 RPM too much? How about 8,ooo?
« Reply #59 on: December 02, 2019, 10:35:38 AM »
BMW speedo's are notoriously inaccurate. Not uncommon to have them indicate 6mph/10 km over the indicated speed at 62mph/100kph so hard to say how far out it is at the upper range. Need somebody with a radar gun or timed run to be more accurate.  GPS units are also more accurate than a vehicles speedo.

The video shown, the bike has the newer gauge cluster, so likely not a 2V. With respect to rear ends the 2V had either a 32/11 or 33/11. Not sure if that ever changed through the various brick models.
  • Alberta Canada
  • 1986 K100RT

Offline Filmcamera

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Re: Is a sustained 7,000 RPM too much? How about 8,ooo?
« Reply #60 on: December 02, 2019, 11:04:04 AM »
I have had my bike at 200 kph on GPS and the speedo was showing just under 140 mph so yeah the speedo is pretty inaccurate on my bike at least.  I know in theory it is possible to calibrate it but I nearly always have gps open so tend to use that to check my speed anyway.  The bike had more speed in it at 200 kph but I ran out of straight road to keep increasing - not many straight roads here in CR and 95% of the time that is a good thing!
  • San Jose, Costa Rica
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Offline beemrdon

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Re: Is a sustained 7,000 RPM too much? How about 8,ooo?
« Reply #61 on: December 02, 2019, 12:12:44 PM »
I had it past the red line once last year while racing a Hardly on 215. It just cut out and died. I'm glad it did or I might have blown the motor.

Also, I had it up to 145 indicated last month. That was just too fast for a 2 lane highway. I was going up a 4% grade and still gaining slowly when I backed off. Full fairing and bags. I think the topcase was on but can't remember exactly.
  • Southern Nevada, close to everything!
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Offline daveson

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Re: Is a sustained 7,000 RPM too much? How about 8,ooo?
« Reply #62 on: December 02, 2019, 08:31:29 PM »
To see if my 30+ year old brick could still do what is claimed when new,  I tried to get it to 200km/h (8,000rpm) It did it easy with throttle to spare,  and that's with three tragkorbs, a taller steeper than usual windscreen and a passenger heavier than me (I'm 90 kg) Sustaining that is something you want to think twice about.

The handling of these bricks gives me more confidence than I probably should have.

It's normal for a speedo reading 100km/h to be clocked at 95 or 96km/h with a speed checker.
  • Victoria, Australia
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Offline Laitch

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Re: Is a sustained 7,000 RPM too much? How about 8,ooo?
« Reply #63 on: December 02, 2019, 08:58:13 PM »
It's like being back in high school. I even think my skin tone is improving!  :twothumbsupp
  • Along the Ridley in Vermont.
  • 1995 K75 72,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline Nine80seven

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Re: Is a sustained 7,000 RPM too much? How about 8,ooo?
« Reply #64 on: December 02, 2019, 09:20:33 PM »
IIRC, all K100RS and K1100RS came with 31/11, 2.81.  Standard K100, K100RT, K100LT, and 1100 RT, LT, came with 32/11, 2.91.  Could be wrong but don't want to get up and look because of turkey hash.

Speedos are always off unless you sent it out to get serviced and calibrated.  The guy servicing the unit has to know yer gear.  Not unusual to have different FD with a different gear, like a 2.91 on an RS. 

Airheads are just as bad.  At least ten percent faster than reality.  Always thought I was going around eighty.  After calibration with  33/11, at 4K, more like 68.  R90S.  FWIW.
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Offline billday

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Re: Is a sustained 7,000 RPM too much? How about 8,ooo?
« Reply #65 on: December 02, 2019, 09:47:00 PM »
K bike  speedos are consistently 10% fast. I  checked that out while running a bicycle speedo which was spot-on (I checked it against those speed warning signs that flash your mph).

A free program called Karamba  works to calibrate your bread box.
  • New York State, USA 10977
  • 1985 K100

Offline The Mighty Gryphon

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Re: Is a sustained 7,000 RPM too much? How about 8,ooo?
« Reply #66 on: December 02, 2019, 09:53:38 PM »
I used Karamba to calibrate three of my speedometers.  What I found with mine was that I had to turn the adjustment pot all the way to the stop to get close to an accurate reading.  Even then, my K75RT speedo still reads a mile or two higher than my GPS when hauling a** across the Great Plains.
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '91K100RS White/Blue, '89 K100RS Special edition White/Blue
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'91 K100RS "Moby Brick Too
'89 K100RS SE

Offline Laitch

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Re: Is a sustained 7,000 RPM too much? How about 8,ooo?
« Reply #67 on: December 02, 2019, 10:22:07 PM »
IIRC, all K100RS and K1100RS came with 31/11, 2.81.  Standard K100, K100RT, K100LT, and 1100 RT, LT, came with 32/11, 2.91.  Could be wrong but don't want to get up and look because of turkey hash.
Your RC seems to be RI. I can't find a K1100RT but the published RS specs differ from your recollection. Also, there were variations among the ordinary 2V. Continue with your flatulence. I'll fill the gap until you resume consciousness. :-)

  • Along the Ridley in Vermont.
  • 1995 K75 72,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

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