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Author Topic: Engine swap K75S 740cc trade for a 987cc from a k100  (Read 8321 times)

Offline Devil K

  • Motobrick Curious
  • Posts: 40
Engine swap K75S 740cc trade for a 987cc from a k100
« on: June 10, 2016, 05:08:54 PM »
Do you guys think it's possible to transplant a k100 motor into a k75 and if so is there a difference in their transmissions, drive shaft, and final drives?
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  • Kernville
  • 1994 BMW K75S

Offline Martin

  • ^ Quintessential Motobricker
  • Posts: 4475
Re: Engine swap K75S 740cc trade for a 987cc from a k100
« Reply #1 on: June 10, 2016, 05:20:51 PM »
Front down tubes are different, probably cheaper to buy a K100 and sell the K75. Transmission drive shaft and final drive ( different ratio ) will fit.
Regards Martin.
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  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline K1300S

  • ^ Quintessential Motobricker
  • Posts: 1293
Re: Engine swap K75S 740cc trade for a 987cc from a k100
« Reply #2 on: June 10, 2016, 07:24:27 PM »
Nor will the 4cyl fit under the S bodywork....
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Project Thread "K75s Midlife Refresh"
http://www.motobrick.com/index.php/topic,7810.0.html

Offline Martin

  • ^ Quintessential Motobricker
  • Posts: 4475
Re: Engine swap K75S 740cc trade for a 987cc from a k100
« Reply #3 on: June 10, 2016, 10:04:38 PM »
 Marshall about 12 years ago there was a guy in the BMWMCQ who did fit K75s fairing to a K100 minus the belly pan. I have looked for pictures on their website but have been unable to find them.
Regards Martin.
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  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline K1300S

  • ^ Quintessential Motobricker
  • Posts: 1293
Re: Engine swap K75S 740cc trade for a 987cc from a k100
« Reply #4 on: June 10, 2016, 10:25:18 PM »
That is only part of the package.   No complete S fairing. ...it doesn't count!
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Project Thread "K75s Midlife Refresh"
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Offline Martin

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  • Posts: 4475
Re: Engine swap K75S 740cc trade for a 987cc from a k100
« Reply #5 on: June 10, 2016, 10:34:45 PM »
Does so, some K75s did not come with a belly pan, it was originally optional, so there. Nana nana nah nah. :neener:
Regards Martin
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  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline Martin

  • ^ Quintessential Motobricker
  • Posts: 4475
Re: Engine swap K75S 740cc trade for a 987cc from a k100
« Reply #6 on: June 10, 2016, 11:44:23 PM »
Marshall just for you I finally found a picture of the K100s and it had a belly pan.
Regards Martin.
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  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline jakgieger

  • itinerant farmer
  • ^ SuperNatural Motobricker
  • Posts: 618
Re: Engine swap K75S 740cc trade for a 987cc from a k100
« Reply #7 on: June 11, 2016, 08:00:22 AM »
K100 belly pan... :bmwsmile like on my avatar
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  • Kansas USA
  • 1989 K100rs se
"What we've got here is failure, to communicate.  Some men, you just cain't reach.  So you get what we had here last week.  Which is the way he wants it...Well, he gets it.  I don't like it any more than you men do."

Offline Devil K

  • Motobrick Curious
  • Posts: 40
Re: Engine swap K75S 740cc trade for a 987cc from a k100
« Reply #8 on: June 11, 2016, 02:43:34 PM »
So my question is, is there anyone out there who could give me advice on the motor swap. And you are saying that it is possible?
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  • Kernville
  • 1994 BMW K75S

Offline johnny

  • TrailBrakingThrottleWhacker
  • ^ Quintessential Motobricker
  • Posts: 7652
  • Whacking...n...Chopping Sliding...n...High Siding
Re: Engine swap K75S 740cc trade for a 987cc from a k100
« Reply #9 on: June 11, 2016, 02:46:45 PM »
greetings devil k...

it is possible with the right shop equipment... plasma cutter... tig welder... tube bender... frame table and so forth...

j o
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  • :johnny i parks my 96 eleven hundert rs motobrick in dodge county cheezconsin  :johnny

Offline Martin

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  • Posts: 4475
Re: Engine swap K75S 740cc trade for a 987cc from a k100
« Reply #10 on: June 11, 2016, 04:51:02 PM »
+1 Johnny but anything  is possible, but it will require modifying the frame, a procedure that should be done by experienced persons.
Martin.
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  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline bmwrn

  • Curious
  • Posts: 5
Re: Engine swap K75S 740cc trade for a 987cc from a k100
« Reply #11 on: February 13, 2017, 07:52:21 PM »
  I think that the K75RT frame is a K100 frame. The radiator shroud from a K100 bolts on to a stripped RT. I understood that the K75 RT was built on the K100 frame to save reengineering the K75RT.
  I d[size=78%]on't have a reference for this, only my experience with my stripped RT :2thumbup: [/size]
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Offline Chaos

  • Administrator
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  • Posts: 3157
  • Mars needs women!
Re: Engine swap K75S 740cc trade for a 987cc from a k100
« Reply #12 on: February 13, 2017, 08:15:15 PM »
I bet a 3 cylinder turbo diesel from a smart car would fit.
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  • sw ohio
1987 K75S    VIN 0231
Original owner, Original litter
200,000 miles (plus or minus) and 5 paint jobs
sold 6/23
2023 Ural 2WD sidecar (BMW's bastard step child)

Offline Martin

  • ^ Quintessential Motobricker
  • Posts: 4475
Re: Engine swap K75S 740cc trade for a 987cc from a k100
« Reply #13 on: February 13, 2017, 10:29:40 PM »

bmwrn definitely different front down tubes between a K75 and a K100.
Regards Martin.
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  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline Dennis de Vries

  • ^ Motobrick Curious
  • Posts: 106
Re: Engine swap K75S 740cc trade for a 987cc from a k100
« Reply #14 on: February 14, 2017, 01:27:46 AM »
As mentioned a few times now, the downtubes are different as the k75 lump is one pot short but you are welcome to prove us wrong. You are right on the k75rt running a k100 rad but that has been done to prevent it from overheating when touring fully loaded 2 up in a hot environment... Bit overkill if you ask me...

Verstuurd vanaf mijn HUAWEI CUN-L21 met Tapatalk

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  • Holland, Europe
  • '89 K75RT
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