Author Topic: 1991 K75S - 30 year major service  (Read 9243 times)

Offline Laitch

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Re: 1991 K75S - 30 year major service
« Reply #25 on: September 30, 2020, 06:25:18 PM »
Probably not as much of a problem with LH drive roads
It depends upon whether you're wearing your sword. Regardless, here are some fun facts.
  • Along the Ridley in Vermont.
  • 1995 K75 86,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline mw074

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Re: Tues, 9/29 progress
« Reply #26 on: September 30, 2020, 08:20:08 PM »
I use a mixture of 50/50 boiled linseed oil and mineral spirits (paint thinner). 

 Dahm, just use Armor All.
  • Michigan

Offline kurtk75s

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Re: 1991 K75S - 30 year major service
« Reply #27 on: September 30, 2020, 08:59:52 PM »
If that works for you, go for it. 
  • Syracuse, NY
  • 1991 K75S

Offline kurtk75s

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Fuel tank
« Reply #28 on: September 30, 2020, 09:18:19 PM »
I'm sure you know what you are looking at.
  • Syracuse, NY
  • 1991 K75S
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Offline Martin

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Re: 1991 K75S - 30 year major service
« Reply #29 on: September 30, 2020, 09:21:20 PM »
A US company called Surf City makes some really good products. Surf City Black Max  on the plastic doesn't attract dust like Armor All. The only down sides are you have to reapply if it rains and the only place I can get it is from a Hardly Ableto shop. I might be developing an obsession with their products, the last time I needed Black Max I bought a gallon.
Regards Martin.

* Surf City Polish.jpg (46.57 kB . 768x576 - viewed 412 times)
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline Laitch

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Re: Fuel tank
« Reply #30 on: September 30, 2020, 10:17:30 PM »
I'm sure you know what you are looking at.
Toilet tank mechanisms have certainly improved over the years!
  • Along the Ridley in Vermont.
  • 1995 K75 86,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline kurtk75s

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Black Plastic
« Reply #31 on: September 30, 2020, 10:59:23 PM »
I guess my pictures don't do the parts justice since I'm getting suggestions on what products I should have used. 

I'm going to stop posting detailing pictures.  If I have any interesting things pop up when I dig into the mechanical stuff, I'll add them to the thread.   
  • Syracuse, NY
  • 1991 K75S

Offline Martin

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Re: 1991 K75S - 30 year major service
« Reply #32 on: October 01, 2020, 01:28:59 AM »
Kurt there's nothing wrong with your cleaning methods the results look good. I just don't like Armor All all that much.
Regards Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline kurtk75s

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Tire Install
« Reply #33 on: October 01, 2020, 02:37:52 PM »
My project is boring - even to me.  So far this has just been 'work'.  And I really don't plan on doing anything that I haven't done before.  But I'll throw out some pictures of my tire mounting and balancing setup. 

Lately I've only been mounting sport bike sized radials (120 F/ 180 R) on a few of our other bikes.  Since the K75 was in California, I would take the wheels in to a shop and have tires put on since I didn't have the tools out there.  I forgot how easy it is to mount tires on the K75 rims.  My set up is basic - I just use a milk crate, some Quick Clamps and a lot of RuGLYDE.  My rim protectors are just cut out of a jug of some sort.  I've been using the same ones for years.  I have a few tire irons but for this install, I only need one.  It is a long one but I didn't need the leverage - it has a bend in it, which makes sliding tire over it super easy.  You can kind of see that in the picture.  There is no grunting or swearing with this method.  The beads popped really easy.  Maybe because the tires had been installed before.  Didn't even remove the cores.

For tires, I put on the Shinko 712s that were on the wheels previously.  They have 2 weeks/~4k miles of use.  There is still plenty of meat left.  They were one of the few tires I could get delivered to the shop within 10 days when I ordered them in 2017.  I was skeptical because of the low price but I was pleasantly surprised with the performance.  I didn't do a lot of mountain riding but I did some while in Az/NM/Big Bend/Talamina to Ak and then down to the Natches trace up through Tn, Wv, PA, etc.   Enough varied roads and rain that I was able to get an idea of what they are capable of.   I liked them enough that I may get them again if they stay consistent over the next 2k or so miles.

The rear only required 14g of weight to static balance.   I haven't done the front yet.  Need to install the new rotors first.  Got the ABS ring off the old one and now I have to attach it to the new, which is cooling down right now.

Brake lines should arrive tomorrow so the front end should be going back together very soon. 
  • Syracuse, NY
  • 1991 K75S

Offline The Mighty Gryphon

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Re: 1991 K75S - 30 year major service
« Reply #34 on: October 01, 2020, 03:02:23 PM »
I like that setup for mounting the tire. 

712's are nice tires.  I've run a couple sets so far and can't find anything wrong with them except that the front with that center groove kinda likes wobbling a little on rain grooves.  Have a new set on my K100RS.  I've found that Shinkos don't need a lot of weight to balance.

Just wondering, do you check the balance of the wheel before you put the tire on it?  I've recently discovered that on my BMW wheels the heavy spot isn't at the valve stem.  Sometimes it can be as much as a quarter of the way around the wheel from the valve.  Putting the dot on that heavy spot makes balancing a little easier.

  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline alabrew

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Re: 1991 K75S - 30 year major service
« Reply #35 on: October 01, 2020, 04:03:07 PM »
I have a Metzeler balancer, but mine is a metal box with a sliding drawer where you store the support arms, they screw onto the lid, and axle.
  • Birmingham, Alabama
  • 1985 K100, 1991 K100RS
Also:
2005 K1200LT
1979 R65
200,000 miles on BMW motorcycles

Offline kurtk75s

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Re: 1991 K75S - 30 year major service
« Reply #36 on: October 01, 2020, 04:16:43 PM »
Normally I do check where the heavy spot on the wheels is.  I didnít this time because the tire isnít marked.  My experience is the same as yours.  Not just on BMW rims.

 I can never remember if the Ďdotí is the light spot or the heavy spot.  Always have to look that up.

Do you remember the Dunlop K491s?  I loved those Harley tires.  Really long wear and consistent feel.  I was sad when they stopped making them.  Many of the replacements ended up with weird cupping on the front so I would replace them earlier than the tread suggested.  No problem with the Shinkos so far.  All of our other BMWs wear Michelin Pilot Roads.  4GT now and the 3s before.  So I am willing to pay for good tires.  It is nice to not have to, though.
  • Syracuse, NY
  • 1991 K75S

Offline kurtk75s

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Re: 1991 K75S - 30 year major service
« Reply #37 on: October 01, 2020, 04:24:47 PM »
Alabrew, yours looks much nicer than mine.  I can’t remember when I picked mine up but it was in the 90s.  2 other riding buddies got the same one because we got a good deal on them.  I bought the metzler rear wheel adapter and that was really expensive.  The other 2 guys made measurements from mine and machined theirs on a lathe and milling machine one of the guys owned.  In the long run, mine was probably a lot less expensive  :laughing1:
  • Syracuse, NY
  • 1991 K75S

Offline kurtk75s

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Re: 1991 K75S - 30 year major service
« Reply #38 on: October 01, 2020, 04:29:21 PM »
Yes haw, I can edit posts now!
  • Syracuse, NY
  • 1991 K75S

Offline alabrew

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Re: 1991 K75S - 30 year major service
« Reply #39 on: October 02, 2020, 03:53:02 PM »
I put the dot at the (metal) valve.
Yes, Dunlop K491 tires were the tire back in the day for me too.
I bought my balancer in the early 2000's from a GW site for about $100, iirc.
I bought two tires, a HF tire changing stand with motorcycle adapter, and the balancer for what it was going to cost to have two tires put on at the dealer.
  • Birmingham, Alabama
  • 1985 K100, 1991 K100RS
Also:
2005 K1200LT
1979 R65
200,000 miles on BMW motorcycles

Offline The Mighty Gryphon

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Re: 1991 K75S - 30 year major service
« Reply #40 on: October 03, 2020, 01:07:09 AM »
I put the dot at the (metal) valve.

Next time find the actual heavy spot on the wheel.  You might be surprised at where it is.

The old steel wheels with spokes were built from a metal extrusion that had pretty consistent density and weight.  Alloy wheels are molded, and core shift in the mold as well as pressure drop across the mold cavity can make for uneven density in the finished part. 

Since I started matching the light part of the tire to the real heavy spot in the wheel balancing goes a lot faster for me.  Definitely worth the extra 5-6 minutes that the extra step takes.  If you mark it with a discrete dot of paint, you'll only have to find it once.
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline kurtk75s

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more tire stuff
« Reply #41 on: October 03, 2020, 08:48:48 AM »
I got the new rotors mounted on the front wheel and got it balanced:  it required 14g, just like the rear. 

Also got the Spiegler lines mounted on the front.  This weekend I should have the front end back together.  I think I'll take a little breather before starting in on the back end.

Before getting the Metzeler balancer, I used a method that my father-in-law showed me:  he would get the axel level between two jack stands and then use that setup to balance the wheel.  That worked great for me - until I got a bike with a single sided swingarm.   My first tire change on the k75 resulted in a balanced front wheel and unbalanced rear wheel.  Then I started looking for a solution.
  • Syracuse, NY
  • 1991 K75S

Offline Laitch

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Re: 1991 K75S - 30 year major service
« Reply #42 on: October 03, 2020, 10:23:11 AM »
That worked great for me - until I got a bike with a single sided swingarm.   My first tire change on the k75 resulted in a balanced front wheel and unbalanced rear wheel.  Then I started looking for a solution.
What was your solution?
  • Along the Ridley in Vermont.
  • 1995 K75 86,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline Chaos

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Re: 1991 K75S - 30 year major service
« Reply #43 on: October 03, 2020, 02:29:52 PM »
I never used to balance my MC wheels and never had a problem, recently got a HF wheel balancer (mainly for trueing up the spoked wheels on my Ural) but still never balanced the rear on the K.  Many people use balance beads or other easy fixes, not me.  I read somewhere about the dynamics of balancing and car tires suffer the most from being out of balance, but for some esoteric reason large truck and MC tires not so much.  I forget the mathematics and physics involved but it was on the internet and it makes me feel better about not balancing that back tire. 
  • 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 kurtk75s

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Re: 1991 K75S - 30 year major service
« Reply #44 on: October 04, 2020, 12:02:45 PM »
Laitch - see last picture in reply #33.  Metzeler balancer with BMW adapter that we are discussing.
  • Syracuse, NY
  • 1991 K75S

Offline kurtk75s

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Re: 1991 K75S - 30 year major service
« Reply #45 on: October 04, 2020, 12:10:05 PM »
Chaos, I have no experience with issues due to unbalanced wheels.  I think I've only had one unbalanced wheel on any of my bikes throughout my entire riding life, though.   :bmwsmile

The internet is always right:  if you look long enough.  The problem is that you can also always find the wrong answer if you look long enough.

I wish I had the time to read the whole internet.  Maybe it would have prevented gear oil from exiting my clutch pushrod boot when I released the clutch arm while changing the cable. 

Experience is the teacher that gives the test first, then the lesson.

  • Syracuse, NY
  • 1991 K75S

Offline Laitch

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Re: 1991 K75S - 30 year major service
« Reply #46 on: October 04, 2020, 10:38:01 PM »
I wish I had the time to read the whole internet.  Maybe it would have prevented gear oil from exiting my clutch pushrod boot when I released the clutch arm while changing the cable.
Probably not.  Only an unripped, securely fastened boot that wasn't hyper-extended would have prevented that. :laughing4-giggles:
  • Along the Ridley in Vermont.
  • 1995 K75 86,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline kurtk75s

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Splines
« Reply #47 on: October 05, 2020, 10:14:26 PM »
I have the bike in a position to take the transmission off.  The front end of the bike is back together and looking good.  I'm glad I did that first because I needed some momentum with the project before confronting the condition of the drive shaft splines.

The splines on both the drive shaft and the pinion shaft are toast.  I will take some pictures tomorrow when there is more light.  My phone doesn't do well with close ups in low light.   

I knew that this was going to be the case - which is why the bike has been sitting on a lift for 3 years.  If I had taken the final drive off first, I may have just parted the bike out.  The bike isn't worth much, especially with expensive repairs needed.  But now I'm 'in for a penny, in for a pound'. 

I'm hoping that there are no surprises when I remove the gear box. 

Since I had my hands on the rear master cylinder, I took the piston out.  I'm going to try to clean it up before getting a new one.  The seals look pretty clean and no rips.  I'll try to smooth out the cylinder bore with some really fine sandpaper and a round drift.   I've had that work OK on other old bikes.  What's the worst that can happen?   
  • Syracuse, NY
  • 1991 K75S

Offline Laitch

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Re: 1991 K75S - 30 year major service
« Reply #48 on: October 05, 2020, 11:09:53 PM »
I'll try to smooth out the cylinder bore with some really fine sandpaper and a round drift.   
I used a piece of Scotchbrite red pad to dress my front master cylinder's boreórolled up until it fit snugly. No grit residue.
  • Along the Ridley in Vermont.
  • 1995 K75 86,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline The Mighty Gryphon

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Re: 1991 K75S - 30 year major service
« Reply #49 on: October 05, 2020, 11:31:27 PM »
If need be, you can get a rear master cylinder that will work nicely from Covidland for about 13-14 bucks.  I've put three of them on my bikes so far and they all work great.  One has nearly 25,000 miles on it.

There's a thread around here that discusses how to do it.
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

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