Author Topic: K100RS Frames-What's the difference?  (Read 1057 times)

Offline The Mighty Gryphon

  • ^ Quintessential Motobricker
  • Posts: 4403
K100RS Frames-What's the difference?
« on: November 29, 2017, 11:04:59 AM »
I've decided to restore Moby Brick to pre butt f-ed glory.  In the weeks since the attack I've been able to cop almost all the parts needed at incredibly good prices(Many thanks to all the guys who are cappucino-izing their bricks).

One problem I am wrestling with now is the frame.  The rampaging Kia that attacked me managed to tweak the rear loop and kink/collapse the frame tube where the VIN sticker is attached.   A couple phone calls have convinced me that frame straightening is out of the budget(by a lot!) so I have started shopping for a frame.

A quick search of eBay presents about a dozen K100 frames, many with clear title, from '85 to '91 ranging in price from $70 to $800.  Of course, it's the '91, which is a direct replacement for Moby Brick's frame that is $800. 

I have been researching the differences between the two frames(2v vs. 4v) and all I can find is that the 4v frame does not have the mounting points for the Jetronic system components.  All the other components and body panels attached to the frame are the same and use the same mountings.

So, my questions are:

1. Can anyone document any reason why a 2v frame from the late '80's can't be used to build a Motronic 4v K100RS without ABS? 

2. Has anyone actually put a 4v K100 engine with Motronic into a 2v K100 frame?  Were there any issues with the swap?

3. Is there any difference in the front end geometry of the steering head that may cause handling problems with the 4v forks?
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '91K100RS White/Blue
'94 K75RT "Ilsa, She Wolf of the SS"
'91 K100RS "Moby Brick Too

Offline Martin

  • ^ Quintessential Motobricker
  • Posts: 3705
Re: K100RS Frames-What's the difference?
« Reply #1 on: November 29, 2017, 03:40:42 PM »
Gryph if you can't find anyone who can supply the wanted information. See if you have a 2v and 4v frame for sale locally, then see if they will let you take photo's and measurements and compare. However you would think that somebody had already travelled that path. Good luck.
Regards Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.