Author Topic: '87 K75 Revival....maybe.  (Read 8700 times)

Offline gofargogo

  • ^ Motobrick Curious
  • Posts: 50
'87 K75 Revival....maybe.
« Reply #25 on: January 15, 2018, 01:26:20 PM »
120 miles total yesterday. The seat is a plank, but the bike is sweet.

Can anybody take a photo of their Corbin seat hardware setup? I have a stock seat and a Corbin, but I知 pretty sure I知  missing hardware.

Sent from my iPhone using Tapatalk
  • Santa Rosa, CA
  • 1987 K75s
1987 K75s, my first brick

Offline The Mighty Gryphon

  • ^ Quintessential Motobricker
  • Posts: 4410
Re: '87 K75 Revival....maybe.
« Reply #26 on: January 15, 2018, 03:30:20 PM »
You need to swap the hardware over.  Seat hardware is so costly that almost no one sells a seat complete with it.
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '91K100RS White/Blue
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'91 K100RS "Moby Brick Too

Offline gofargogo

  • ^ Motobrick Curious
  • Posts: 50
Re: '87 K75 Revival....maybe.
« Reply #27 on: January 15, 2018, 03:45:56 PM »
I知 pretty sure I知 missing pieces on my stock seat. I think there should be a limit strap or something. The fisch was confusing as to what my particular bike would normally have.




Sent from my iPhone using Tapatalk
  • Santa Rosa, CA
  • 1987 K75s
1987 K75s, my first brick

Offline Laitch

  • ^ Quintessential Motobricker
  • Posts: 6407
Re: '87 K75 Revival....maybe.
« Reply #28 on: January 15, 2018, 05:34:05 PM »
I知 pretty sure I知 missing pieces on my stock seat. I think there should be a limit strap or something. The fisch was confusing as to what my particular bike would normally have.
The seat swivels on two hinges mounted on the edge opposite the latch post. The arrow indicates one of those side hinges. The seats travel is stopped by the extension of a hinged support arm one end of which mounts to a pin on the frame between the side rails. The other end of the arm is attached by a pin and clip to the hole at other the end of the metal strap.




From MAX BMW'S parts fiche.
  • Along the Ridley in Vermont.
  • 1995 K75T 68,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline Martin

  • ^ Quintessential Motobricker
  • Posts: 3706
Re: '87 K75 Revival....maybe.
« Reply #29 on: January 15, 2018, 06:11:06 PM »
The clips no 15 tend to get lost. They can be substituted with an "R" clip which can be either bought or made. They can be bought from hobby shops and are used for fixing the body shells on RC cars. A hole of the correct diameter needs to be drilled in the slot where "C" clip resided. I also have a piece of wire with a small hook at one end and a finger loop at the other. This makes removal of the "R" clips and the fuel tank "C" clips easy. It resides under my seat along with spare "R" clips sandwiched between Velcro.
Regards Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline TaosBrick

  • ^ Proficient Motobricker
  • Posts: 462
  • RedHotMotoBricker
Re: '87 K75 Revival....maybe.
« Reply #30 on: January 15, 2018, 11:09:14 PM »
You mentioned "repairing" your FD/Driveshaft splines. Did you mean replace, or actually repair? If you mean repair, you must have Mad Jedi Machinist Skilz, alright.
Flog It Every Day - I mean, the BIKE!
'92 K75, '73 R75/5 Caf,'89 Yam XT350
Expect Nothing, Be Ready For Anything.
- Samurai Maxim

Offline Laitch

  • ^ Quintessential Motobricker
  • Posts: 6407
Re: '87 K75 Revival....maybe.
« Reply #31 on: January 15, 2018, 11:12:01 PM »
Here is a more explanatory photo.

  • Along the Ridley in Vermont.
  • 1995 K75T 68,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline gofargogo

  • ^ Motobrick Curious
  • Posts: 50
Re: '87 K75 Revival....maybe.
« Reply #32 on: January 15, 2018, 11:14:33 PM »
You mentioned "repairing" your FD/Driveshaft splines. Did you mean replace, or actually repair? If you mean repair, you must have Mad Jedi Machinist Skilz, alright.
I was looking at that shaft piece that motobins sells. I know some good machinists locally that shouldn稚 have any problem cutting and rewelding the shaft.


Sent from my iPhone using Tapatalk
  • Santa Rosa, CA
  • 1987 K75s
1987 K75s, my first brick

Offline gofargogo

  • ^ Motobrick Curious
  • Posts: 50
Re: '87 K75 Revival....maybe.
« Reply #33 on: January 15, 2018, 11:15:09 PM »
Here is a more explanatory photo.


Thank you. This helps a lot. I have everything but the stay (and clips)


Sent from my iPhone using Tapatalk
  • Santa Rosa, CA
  • 1987 K75s
1987 K75s, my first brick

Offline Martin

  • ^ Quintessential Motobricker
  • Posts: 3706
Re: '87 K75 Revival....maybe.
« Reply #34 on: January 16, 2018, 01:15:45 AM »
Until you get an OEM one a temporary stay can be made out of a piece of thick coat hanger wire. If you are desperate and have a reasonable workshop and metal skills you could make one from scratch
Regards Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline gofargogo

  • ^ Motobrick Curious
  • Posts: 50
Re: '87 K75 Revival....maybe.
« Reply #35 on: January 16, 2018, 01:17:05 AM »
I was thinking about a length of bicycle chain...


Sent from my iPhone using Tapatalk
  • Santa Rosa, CA
  • 1987 K75s
1987 K75s, my first brick

Offline Laitch

  • ^ Quintessential Motobricker
  • Posts: 6407
Re: '87 K75 Revival....maybe.
« Reply #36 on: January 16, 2018, 01:35:11 AM »
I'm thinking of a number between one and ten.
  • Along the Ridley in Vermont.
  • 1995 K75T 68,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline gofargogo

  • ^ Motobrick Curious
  • Posts: 50
Re: '87 K75 Revival....maybe.
« Reply #37 on: January 16, 2018, 01:42:21 AM »
I'm thinking of a number between one and ten.
7.5?


Sent from my iPhone using Tapatalk
  • Santa Rosa, CA
  • 1987 K75s
1987 K75s, my first brick

Offline TaosBrick

  • ^ Proficient Motobricker
  • Posts: 462
  • RedHotMotoBricker
Re: '87 K75 Revival....maybe.
« Reply #38 on: January 16, 2018, 11:21:54 AM »
I was looking at that shaft piece that motobins sells. I know some good machinists locally that shouldn稚 have any problem cutting and rewelding the shaft.


Sent from my iPhone using Tapatalk


You mean pieces. If you repair the pinion shaft, then you either need to find a new end for the driveshaft (and have it fitted), or buy a new driveshaft.


Far less contortions to find a good '85 K100 Z16 FD and Driveshaft on eBay. (Worked for me  :riding: )


Splicing a new spline end on to a pinion shaft is very exacting work. It cannot be out of kilter by the merest fraction of a millimeter. The only guy I know of in the whole bimmer community that does this on a routine basis is a guy named Bruno, whom I have heard has been ill of late and not working.
Flog It Every Day - I mean, the BIKE!
'92 K75, '73 R75/5 Caf,'89 Yam XT350
Expect Nothing, Be Ready For Anything.
- Samurai Maxim

Offline gofargogo

  • ^ Motobrick Curious
  • Posts: 50
Re: '87 K75 Revival....maybe.
« Reply #39 on: January 17, 2018, 02:26:44 PM »


Splicing a new spline end on to a pinion shaft is very exacting work. It cannot be out of kilter by the merest fraction of a millimeter. The only guy I know of in the whole bimmer community that does this on a routine basis is a guy named Bruno, whom I have heard has been ill of late and not working.


Good point.


But I have another problem now. The bike is skipping badly in second gear. It didn't do that on my first tentative rides, but I took it out this morning intending to ride to the coast, but anything but the most gentle acceleration in 2nd made it skip-clunk.


My initial research tells me this means find a gearbox on ebay. But it wasn't doing this last week, even when I was riding in a 'sporting' manner, and I did just pull the gear box and sparingly lubed the input spline. Could I have screwed something up on reassembly? (I'm usually a decent wrench, but the suddenness of this problem has me doubting)


It also smokes quite a bit on startup, even though I religiously park it on it's center stand. The devil on my shoulder is telling me this particular example may just be worn out.
  • Santa Rosa, CA
  • 1987 K75s
1987 K75s, my first brick

Offline Laitch

  • ^ Quintessential Motobricker
  • Posts: 6407
Re: '87 K75 Revival....maybe.
« Reply #40 on: January 17, 2018, 02:38:04 PM »
The bike is skipping badly in second gear. It didn't do that on my first tentative rides, but I took it out this morning intending to ride to the coast, but anything but the most gentle acceleration in 2nd made it skip-clunk.
My initial research tells me this means find a gearbox on ebay.
Which research is that?

If you haven't replaced the components with driveline splines that are pictured in this post, your bike is skipping badly because the driveline splines are worn. Eventually your bike won't skip; it will just stop and howl when torque is applied. That's why they were described as toast.
  • Along the Ridley in Vermont.
  • 1995 K75T 68,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline gofargogo

  • ^ Motobrick Curious
  • Posts: 50
Re: '87 K75 Revival....maybe.
« Reply #41 on: January 17, 2018, 02:45:00 PM »
Which research is that?

If you haven't replaced the components with driveline splines that are pictured in this post, your bike is skipping badly because the driveline splines are worn. Eventually your bike won't skip; it will just stop and howl when torque is applied. That's why they were described as toast.


Process of elimination, and searching on here and other bmw forums. It only skips in 2nd, and not any other gear no matter how much throttle I give it. Since it is confined to one gear and not all of them, that tells me that it's unlikely to be the final drive/driveshaft, but I defer to your experience as this is the first K bike I've had.
  • Santa Rosa, CA
  • 1987 K75s
1987 K75s, my first brick

Offline Laitch

  • ^ Quintessential Motobricker
  • Posts: 6407
Re: '87 K75 Revival....maybe.
« Reply #42 on: January 17, 2018, 03:04:34 PM »
. . .  but I defer to your experience as this is the first K bike I've had.
I have zero experience with your bike so I'll defer back to you but keep your AAA RV/Moto policy in good standing because those splines are likely to break and leave you stranded somewhere soon.

Is the second gear "skip" rhythmic or irregular? Do you feel it through the seat or handlebar?
  • Along the Ridley in Vermont.
  • 1995 K75T 68,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline gofargogo

  • ^ Motobrick Curious
  • Posts: 50
'87 K75 Revival....maybe.
« Reply #43 on: January 17, 2018, 03:09:05 PM »
It happened suddenly and once at first. Pulling onto the highway, in second gear and accelerating it lost power for a fraction of a second and then there was an audible and physical clunk and power came back. The second time was when I began to moderately accelerate out of a corner, another single skip and clunk. I turned around at that point and noticed it was in second both times. I stayed out of second for most of the way home, but as I got to my street and turned a corner I gave it very moderate throttle in second and got multiple skips and clunks for a second or two before I backed off and very gently fed it power.


Sent from my iPhone using Tapatalk
  • Santa Rosa, CA
  • 1987 K75s
1987 K75s, my first brick

Offline Martin

  • ^ Quintessential Motobricker
  • Posts: 3706
Re: '87 K75 Revival....maybe.
« Reply #44 on: January 17, 2018, 03:15:13 PM »
Sounds very much like worn splines. It's an easy job to pull apart and confirm, 45min at most.
Regards Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline Skunky

  • ^ Proficient Motobricker
  • Posts: 362
Re: '87 K75 Revival....maybe.
« Reply #45 on: January 17, 2018, 03:30:10 PM »
Sounds very much like worn splines. It's an easy job to pull apart and confirm, 45min at most.
Regards Martin.

Could be right Martin However it could also be the same as this.

http://www.motobrick.com/index.php/topic,9647.msg80835.html#msg80835
  • Derby GB
  • BMW K100lt
Rebuild it and they will come..
90 K100lt
Triumph Thruxton 900
Honda CB400F

Offline riots100

  • ^ Proficient Motobricker
  • Posts: 147
Re: '87 K75 Revival....maybe.
« Reply #46 on: January 18, 2018, 12:02:31 AM »
Worn 2nd gear transmission dogs and/or 2nd gear dogs not fully seating. (think small overlap at the tips of the dogs)  Maybe time to pull the transmission again and open it up.  Take the opportunity to check the dogs while tightening the grub screw.
  • Los Angeles, CA
  • 1992 K75, 2007 K1200GT, 1991 K100RS
----
BDJ

Offline Filmcamera

  • ^ Quintessential Motobricker
  • Posts: 1294
Re: '87 K75 Revival....maybe.
« Reply #47 on: January 18, 2018, 07:07:49 AM »
Yep sounds like worn dog to me, I had the same thing on mine.  In the end it was far cheaper and easier to buy a new transmission. I got one for $150 from ebay and it takes only takes a few hours to install.
  • San Jose, Costa Rica
  • 1991 K100RS 16v ABS1, 2018 Triumph Street Triple RS 765
Poserbricker

Offline The Mighty Gryphon

  • ^ Quintessential Motobricker
  • Posts: 4410
Re: '87 K75 Revival....maybe.
« Reply #48 on: January 18, 2018, 08:39:13 AM »
Have you drained the trsansmission oil since this problem started?  What does it look like?
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '91K100RS White/Blue
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'91 K100RS "Moby Brick Too

Offline TaosBrick

  • ^ Proficient Motobricker
  • Posts: 462
  • RedHotMotoBricker
Re: '87 K75 Revival....maybe.
« Reply #49 on: January 18, 2018, 10:55:29 AM »
Pull trans, make repairs as suggested above, or find a used one on fleabay n save yer old one for parts, or to mess with so as to figure out how works the bimmer transmission.
Got one for $200 on fleabay when my input splines gave out.
Flog It Every Day - I mean, the BIKE!
'92 K75, '73 R75/5 Caf,'89 Yam XT350
Expect Nothing, Be Ready For Anything.
- Samurai Maxim

Tags: