Author Topic: K75s Two into One Project  (Read 30467 times)

Offline Scud

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K75s Two into One Project
« on: November 14, 2015, 09:15:27 PM »
I did a fly and ride recently and picked up a 1992 K75s.  http://www.motobrick.com/index.php/topic,7539.0.html  While looking for parts on Craigslist a couple days ago, I chanced upon a complete 1990 K75s, same color, for an attractive price. So... now I have two bikes, which I am going to merge into one.

The 1992:
40,000 miles, runs very well, but is a bit rough cosmetically, including a lot of corrosion. I rode it over 700 miles and have noted a few minor flaws that can be fixed. And it's got some deferred maintenance, oil leak, dead shock, crappy 10-year old tires, etc.

The 1990:
180,000 miles, but nobody told the engine it's supposed to wear out, it runs about the same as the one with 40,000 on it. However the 2nd gear is skipping in a way that makes we wonder if the whole tranny is going to lock up. The bike was a commuter, well cared for, and garaged - so it's not corroded. But I think she's about at the end of her useful life; the previous owner was concerned about a few other mechanical things too and decided it was not worth trying to keep it going.

The plan:
Dissemble the 1990. Address the deferred maintenance, including spline lube and oil leak, on the 92, reassemble with the "best of both bikes" parts.

So far the intended transfers from 90 to 92 are:
Tires (new Conti-Gos) - and maybe the wheels too. I think I like the look of the older wheels better, and the paint on the 92's wheels is quite bad.
Fork tubes - the 92s are badly pitted
Gas Tank - the 92 has a difficult dent on RH side and had been sitting a while, the 90 has only a small dent and never got a rest - so I think the internals are probably better.
Corbin Seat - but needs recovering
Complete exhaust - 92's is corroded
Square mirrors - again, I think the older style is more attractive than the lollipops on the 92.
All manner of small covers, brackets, fasteners - basically, whatever is nicer will get moved over.

I suspect I will have a bunch of questions along the way, and I will report in whenever I make some significant progress. Please feel free to make suggestions along the way.

First question - is there any reason I should not use the older style wheels on the 1992 bike?

Some pics:





  • Carlsbad, CA
  • 1992 K75s. 2002 Moto Guzzi V11 Scura, 2003 Moto Guzzi V11 LeMans. 2007 Husqvarna TE450

Offline Chaos

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Re: K75s Two into One Project
« Reply #1 on: November 14, 2015, 10:29:38 PM »
The older wheels are actually stronger than the 3 spoke ones.  Looks like you'll have a gold mine of parts to ebay away.
  • sw ohio
1987 K75S    VIN 0231
Original owner, Original litter
200,000 miles (plus or minus) and 5 paint jobs
2012 Ural 2WD sidecar (BMW's bastard step child)

Offline orforester

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Re: K75s Two into One Project
« Reply #2 on: November 15, 2015, 01:19:42 PM »
The reason for using the three spokes as I understand it is radial tires!  IF you can swap to use radials I would dooooo ITTTTTTTTT. read numerous tire threads here, but what I get from them is the snowflake wheels do not take radials, not designed too, and the three spoke wheels were.  Just what I gather from reading, no actual experience, but I am sure someone will correct me if I am wrong.  Swapping parts is fun, been there done that.  Have fun

Bob
Bob
1989 K 100 RS se (SOLD)
1985 K 100 RS, now RT
1979 XS 650 Yamaha Street Tracker
2008 R 1200RT

Offline Scud

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Re: K75s Two into One Project
« Reply #3 on: November 15, 2015, 07:21:56 PM »
Thanks for the wheel and tire info. Today I swapped the wheels - the older wheels cleaned up really well. I've only heard "snowflake" used to describe an older wheel style (which I had on a 1981 R100CS). The older K-bike wheels, I'll call them "Y-spoke", cleaned up really well and it was a breeze to swap rotors (and keep the ABS ring).

I just had a set of Shinko 230s delivered, which are an aramid-belted radial. I have never used Shinko before and thought I 'd try a set. So... now I wonder if I should mount those on the Y-spokes or not. The current Conti Go rear has a lot of life left, but I noticed that the front is badly cupped and I'd like to replace that soon.

I don't mean to turn this into a "tire thread".....  but I searched a bit and found this recent thread, in which some people indicate they have run radials on the Y-spokes:  http://www.motobrick.com/index.php/topic,6585.0.html

If somebody is aware of a thread with an explanation of why radials should not be mounted to Y-spokes, please post a link.



I also installed a new Progressive shock. I didn't bother measuring suspension sag yet - just set the shock in the middle of the pre-load. Now the front feels a bit soft... maybe I'll get some "matching" Progressive springs (like they kindly suggested in the paperwork included with the shock...)

Parts swapping is fun - I already found a few little missing bits and moved them over.

Today's BIG news: 
The Previous Owner of the '92 was told (via an inspection report) that the bike had an oil leak between engine and tranny - and it would take 15 hours labor plus some parts to fix. This was his reason for selling at a fairly low price. I pulled the belly pan to start looking for myself. The oil drain plug was finger-loose and obviously leaking. I snugged it up, rode it around the block a few times and no longer see evidence of an oil leak. I'll give it a week of commuting to be sure, but holy crap - what kind of inspection doesn't even check to see if the drain plug is the cause of the leak?????  Lucky me.
  • Carlsbad, CA
  • 1992 K75s. 2002 Moto Guzzi V11 Scura, 2003 Moto Guzzi V11 LeMans. 2007 Husqvarna TE450

Offline Tuco

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Re: K75s Two into One Project
« Reply #4 on: November 15, 2015, 08:40:48 PM »
Unbelievable on the drain plug!
  • Waldport, Oregon
  • '87 K100LT, '87 K100RS, '97 DR350

Offline rbm

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Re: K75s Two into One Project
« Reply #5 on: November 15, 2015, 09:42:35 PM »
Duck confirmed in 2013 that radials could be gotten for the snowflake rims, Bridgestone BT-023 for the front and Avon AV46 for the rear.  IMO, I believe using the 3-spoke rims is a better idea because the three-spoke rims will have a greater selection of radial tires available and probably more future-proof than the snowflake rims.  I'm running Bridgestone T30 Battlax 110/80ZR-18 on the front and Bridgestone T30 Battlax 150/70ZR-17 on the rear of my K75, equipped with 2.50X18 front and 3.00x17 rear 3-spoke rims.
  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline Scud

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Re: K75s Two into One Project
« Reply #6 on: November 15, 2015, 11:18:27 PM »
Thanks for the confirmation. I'm a little confused, though. Let me try to sort this out. First, this bike will be a tour/commute bike for me, not a sports bike - but it'll certainly see some spirited riding. I'm looking for a blend of durability and performance, not for the most sporting tires.

The rear:
Both wheels, 1990 Y-spoke and 1992 3-spoke, currently have a 130/90-17 (Conti and Metzeler), which is the factory-specified tire size. I bought a Shinko 230 in the same size. I swapped the wheels between bikes with no difficulty. Since the same tire is specified for both wheels, I don't see how one wheel would allow more future options than the other.

The front:
The factory spec is 100/90-18 for both years. The 1990 Y-spoke has a Conti 110/80-18 on it now, which is an "equivalent" size tire. The 1992 3-spoke has a Metzeler 100/90-18. I bought a Shinko 230 in a 100/90-18 (factory spec size). Again, the same tire is specified for both Y-spoke and 3-spoke wheels, so I don't understand the difference in future options.

So... not trying to argue here, just trying to understand.
  • Carlsbad, CA
  • 1992 K75s. 2002 Moto Guzzi V11 Scura, 2003 Moto Guzzi V11 LeMans. 2007 Husqvarna TE450

Offline rbm

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Re: K75s Two into One Project
« Reply #7 on: November 15, 2015, 11:43:14 PM »
Good reference page on tire sizes
Another good reference on rims and brakes

Forget what I wrote above; got confused on the future options.  I was thinking back to when I was considering fitting K1200 wheels to my K75.  These rims are wider and therefore more selection in tires are available.
  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline Chaos

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Re: K75s Two into One Project
« Reply #8 on: November 16, 2015, 12:07:11 AM »
Bent rims are more common on 3 spoke wheels, rim is only supported every 120 degrees.  I like the look of the 3 spoke and they're easier to clean but I've hit big things at speed and never dented my Y spokes.
  • sw ohio
1987 K75S    VIN 0231
Original owner, Original litter
200,000 miles (plus or minus) and 5 paint jobs
2012 Ural 2WD sidecar (BMW's bastard step child)

Offline Scud

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Re: K75s Two into One Project
« Reply #9 on: November 16, 2015, 12:25:30 AM »
OK - so I think the rim question might be settled for me. Y-spokes are stronger (objective) better looking (subjective) and there's no difference in availability/application of tires. And since the 3-spokes break more often they'll probably be easier to sell later.  :2thumbup:
  • Carlsbad, CA
  • 1992 K75s. 2002 Moto Guzzi V11 Scura, 2003 Moto Guzzi V11 LeMans. 2007 Husqvarna TE450

Online Laitch

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Re: K75s Two into One Project
« Reply #10 on: November 16, 2015, 07:48:01 AM »
And since the 3-spokes break more often they'll probably be easier to sell later.
Chaos's assertion is related to the bending of rims, Scud, not the breaking of them. Most wheel rims are susceptible to bending if they bang over potholes, curbs or debris with under-inflated tires.
  • 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.

Offline F14CRAZY

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Re: K75s Two into One Project
« Reply #11 on: November 16, 2015, 09:06:16 AM »
  • Grand Rapids, MI
  • '87 K75C
'87 K75C w/ Pichler V1 fairing. LED's, CATZ driving lights, Audiovox cruise, LT top case, tons of other mods by Drake...


Offline Scud

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Re: K75s Two into One Project
« Reply #12 on: November 16, 2015, 09:52:48 AM »
@Laitch - Yes. Bend, not break. Having bent a few dirt bike rims myself, I have never actually broken one. I am guilty of sloppy, casual writing there, like... you know... I was all... you know...

@F14 - thanks for the link. Glad to hear you are happy with those tires - and on the Y-spoke rims too.

I'll at least put the front tire on in the next few weeks. I want to replace the steering bearings and the wheel bearings at the same time. The front brakes pulse a bit so we'll see if new bearings help with that or not - if not, I may be in the market for floating rotors (and pads and maybe some caliper rebuild kits for good measure). I've seen a few posts where people are happy with the EBC rotors - looks like about $500. Is EBC the only (or best) aftermarket option?

I saw some description of the pulsing problem being attributed to the pads and rotors sort of "welding" when they sit for a long time - and this bike sat for a while in the weather. The whole bottom end is fairly corroded. So if this "welding" thing is true, then these rotors may already be damaged.
  • Carlsbad, CA
  • 1992 K75s. 2002 Moto Guzzi V11 Scura, 2003 Moto Guzzi V11 LeMans. 2007 Husqvarna TE450

Offline The Mighty Gryphon

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Re: K75s Two into One Project
« Reply #13 on: November 16, 2015, 10:09:26 AM »
Regarding your Shinko 230 Tourmasters, I have run one on the rear of  my K75RT and have gotten over 10,000 miles on it.  I don't know about the aramid belts, but the 230 is NOT a radial tire.  As far as radial tires for the K75, unfortunately,  there are none readily available at this time that will fit the narrower wheels on these bikes.

One of the characteristics of the BMW wheels is that they are made of a softer, more  malleable alloy that the wheels of the Japanese bikes.  This means that they will bend easier, but the benefit is that they will not crack under heavy impact, and because of that, will not have catastrophic air loss. 

A side benefit of the soft alloy is that with a bit of care, they can be straightened.   With a few blows from a dead blow hammer I was able to take a small dent out of the three spoke front wheel of my K100.



  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '92K100RS White, '94 K75S Dakar Yellow
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'94 K75S "Cheetos"
'91 K100RS "Moby Brick Too

Offline F14CRAZY

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Re: K75s Two into One Project
« Reply #14 on: November 16, 2015, 11:00:45 AM »
Ha my front rotors and pads weld together often. It'll happen after sitting in my carport for a couple days if its raining. I find out as it comes to a halt coming off the center stand. A couple light hammer taps on the rotor and its free though
  • Grand Rapids, MI
  • '87 K75C
'87 K75C w/ Pichler V1 fairing. LED's, CATZ driving lights, Audiovox cruise, LT top case, tons of other mods by Drake...


Offline JcJ TN K75s

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Re: K75s Two into One Project
« Reply #15 on: November 16, 2015, 12:32:40 PM »
Congrats on your new bike Scud. I bought your HES when you parted out your oilhead RT at BMWST.com and may have to hit you up for some K bits as I chase a summer/fall worth of gremlins out of my K.
JcJ
  • Lincoln, TN 37334
  • 1993 K75S? "Stormtrooper" 1999 R1100RTP "Lord Vader"
I am quite sure now that often, very often, in matters concerning religion and politics a man’s reasoning powers are not above the monkey’s.- Mark Twain

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Offline Scud

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Re: K75s Two into One Project
« Reply #16 on: November 16, 2015, 12:48:36 PM »
Congrats on your new bike Scud. I bought your HES when you parted out your oilhead RT at BMWST.com and may have to hit you up for some K bits as I chase a summer/fall worth of gremlins out of my K.
JcJ
Cool - I recognized that crow-bomber image in your profile pic and wondered if that was you. Send me a message or e-mail with a list of what you need. Both bikes run, so I probably have whatever you need - (except I think I'll probably hold the HES for the K75 in reserve). I might not disassemble the 1990 till after Thanksgiving.
  • Carlsbad, CA
  • 1992 K75s. 2002 Moto Guzzi V11 Scura, 2003 Moto Guzzi V11 LeMans. 2007 Husqvarna TE450

Offline Scud

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Re: K75s Two into One Project
« Reply #17 on: November 17, 2015, 11:22:28 PM »
Unbelievable on the drain plug!

Yeah, I can barely believe it myself. The PO had been adding oil regularly and the belly pan was a mess. I stuffed a bunch of paper towels in there right after I bought the bike - to soak the oil out of the belly pan. The oil pooled up again (and I added oil) before I got it home. I was mentally ready for a big, messy job, but I just wiped the whole engine and transmission with a paper towel and there was not a drop of oil anywhere. The leak has totally stopped. It's amazing what a snug plug can do to transform a bike.
I am stoked!  :clap:

@Mighty - thanks for the clarification on the Shinko tires.
  • Carlsbad, CA
  • 1992 K75s. 2002 Moto Guzzi V11 Scura, 2003 Moto Guzzi V11 LeMans. 2007 Husqvarna TE450

Offline Scud

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Re: K75s Two into One Project
« Reply #18 on: November 21, 2015, 10:59:21 PM »
A window of time opened up so I disassembled the 1990 K75s today. Here's the peak of the mess:



The poor old girl is done now... sort of sad, but she had a good life. Bad tranny (known) and I discovered a lot of oil in the cooling system when I drained the water. Lots of other little parts about ready to fail such as fuel lines... but lots of newer, or otherwise useable stuff too. I've got my own little parts counter now - this will be a huge time and money saver.

Little thing worth checking - one of the four fork cross-member bolts was missing. It was on the left side. That's also the side that had the blown fork seal - and the left side of the tire seemed to be cupped a bit more than the right. I don't know if that could be a cause... but I would not have otherwise ever looked to make sure all four bolts were still up under the fender.

After I tidied up, I managed to get the engine and transmission oil changed on the 1992. Engine oil was nasty - looks like the Seafoam did its job..

I used Redline Shockproof Heavy Duty gear oil in the tranny. I also run this in my Guzzis. The raspberry smoothie looking oil absolutely transformed the K75s transmission. Far smoother and quieter shifts. Significantly less effort - even clutchless shifts are feeling good. And neutral is my new best friend. WOW!!! This oil made only a slight difference in my Guzzis (which already have a fabulous 6-speed tranny) - but the difference in the K75 is MASSIVE.

If I can get this kind of transformation in other areas I will be a happy camper. The Progressive shock was also a huge improvement - so I went ahead and ordered a pair of Progressive fork springs to match. Also ordered for the front end: EBC rotors and pads, caliper rebuild kits, wheel bearings, and steering bearings (All-Balls for all bearings). That and new tire (tior?) should make magic up front.
  • Carlsbad, CA
  • 1992 K75s. 2002 Moto Guzzi V11 Scura, 2003 Moto Guzzi V11 LeMans. 2007 Husqvarna TE450

Offline Scud

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Re: K75s Two into One Project
« Reply #19 on: November 23, 2015, 11:39:41 PM »
Installed three new fuel lines today. The ones on the bike were badly cracked. When I noticed it, I called "fire hazard."

This topic was very helpful re fuel lines:

http://www.motobrick.com/index.php/topic,1042.0.html   Thanks.   :2thumbup:

Very nice tips in there, which saved me a few bucks. But more importantly, I got it done on a Monday, when all the dealers are closed.



It was convenient to be able to salvage enough of the OEM screw-type fuel line clamps to replace all the single-use clamps that I cut off. Also moved the '90 gas tank over to the '92. Found another nasty dent on the '92 tank that was previously hidden by the fairing.

Also made a first attempt at getting the ABS to work. Using a multi-meter, I verified the fault at test point 2 as described in one of the ABS threads. Then I tried the reset several times, all to no avail... Then I gave it a lobotomy: took out the brain and the ABS relay. No more flashing red lights on the dash.... ah.... that feels better.

Maintenance question: how often do you all clean the throttle bodies? I assumed I would get into this pretty soon, but then I noticed that both bikes still have the stock, single-use clamps around the airbox boots - so unless somebody put that kind of clamp back on, it suggests they've never been cleaned... and that I am probably going to have to replace the rubber boots.
  • Carlsbad, CA
  • 1992 K75s. 2002 Moto Guzzi V11 Scura, 2003 Moto Guzzi V11 LeMans. 2007 Husqvarna TE450

Offline treehouse99

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Re: K75s Two into One Project
« Reply #20 on: November 26, 2015, 12:36:41 AM »
Great thread, thanks for posting all this w/ links to other useful tips :2thumbup:!
  • Pomona, N.Y.
  • 87 K75, 90 K75S, 09 Vstrom 650, too many Puch mopeds
treehouse

Offline billday

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Re: K75s Two into One Project
« Reply #21 on: November 26, 2015, 07:36:50 AM »
Maintenance question: how often do you all clean the throttle bodies? I assumed I would get into this pretty soon, but then I noticed that both bikes still have the stock, single-use clamps around the airbox boots - so unless somebody put that kind of clamp back on, it suggests they've never been cleaned... and that I am probably going to have to replace the rubber boots.

Cleaning the TBs isn't usually an issue, on K's you do that job to replace the rubber above and below the TBs. There are good threads on here about how to do it, including info on what screw clamps are suitable to replace the Oetiker clamps from the factory.

Happy Thanksgiving everybody!
  • New York State, USA 10977
  • 1985 K100

Offline Scud

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Re: K75s Two into One Project
« Reply #22 on: December 06, 2015, 06:06:28 PM »
Tidying up the tail a bit....
  • Shorter fender from 1990 bike
    Removed stock side and rear reflectors and used mounting holes for blue reflector dots
    Added Moto-Reflective Saddlebag stickers
    Lightly tinted taillight and turn signals with VHT Nightshades paint
Also got both seats recovered at a local shop. Put the stocker back on for now, will probably end up using the Corbin - all depends on which one my wife finds more comfortable.



The supplies and parts (bearing, rubber, etc.) are queueing up... and I'm waiting on a nice box of goodies from Max's BMW...

Meanwhile, she's been a good commuter and airport runner - I've got a lot of business travel over the next couple months.

Free motorcycle parking at LAX - I love how they say to just ride around the barrier and don't take a ticket.
 http://www.lawa.org/welcome_lax.aspx?id=8702

  • Carlsbad, CA
  • 1992 K75s. 2002 Moto Guzzi V11 Scura, 2003 Moto Guzzi V11 LeMans. 2007 Husqvarna TE450

Offline D.Bachtel

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Re: K75s Two into One Project
« Reply #23 on: December 06, 2015, 10:27:40 PM »
Coming along nicely Tim :2thumbup:
  • Nipomo
  • BSA, Zundapp, Husqvarna, Greeves, Triumph...and a 1987 K75C

Offline Scud

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Re: K75s Two into One Project
« Reply #24 on: December 18, 2015, 09:30:06 PM »
It looks like I am going to have some playtime soon. I've accumulated some parts, paint, and even some Staburags for the spline lube. I will pick up a few parts from the powder-coater early next week. Need to box up the rest of the 1990 parts so I can use my lift again. Meanwhile, here are a some areas where I would appreciate some advice:

Forks: It seems the forks are not the same from a 1990 and a 1990 (both K75s). From what I can gather, the Showa forks from the 1992 are the most desirable. However the tubes are pitted, and I had hoped to use the clean tubes from the 1990. Is this possible - or are these forks totally incompatible with each other? FYI - I have Progressive springs to install, and I said I had a 1992 K75s when I placed the order from Max's BMW.

Wiring: I've decided to eliminate the ABS. Given that I am going to dig pretty deep into the bike to clean it up, paint some things, and lube other things, swapping wiring harnesses wouldn't be a lot of extra effort. However, the 1990 and 1992 relay boxes look very different inside. The 1990 was a non-ABS bike - and did not have a flasher switch. I'm not aware of any other differences. Is there any significant difference in quality, reliability, cost of replacement relays, etc. between a 1990 and 1992 wiring harness? Of course, I could leave the 1992 harness in place, but since I am ditching the ABS, it would be nice to remove all the related, and unneeded wiring.

ECUs: Are the 1990 and 1992 ECUs the same - or is one more desirable than the other?
  • Carlsbad, CA
  • 1992 K75s. 2002 Moto Guzzi V11 Scura, 2003 Moto Guzzi V11 LeMans. 2007 Husqvarna TE450

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