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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => Project Classic Motobricks => Topic started by: gofargogo on January 08, 2018, 11:52:13 AM

Title: '87 K75 Revival....maybe.
Post by: gofargogo on January 08, 2018, 11:52:13 AM

A little over a week ago, I finally called on a craigslist ad I'd been watching for a month. It was an 87 K75s that had been running when parked 5 years ago. It was pretty rough, cracked fairings, oil leak, broken turn signals, old gas, dead battery..etc but he was only asking $600. Due to some back registration, we negotiated down to $500 and I loaded it up.

It's my first brick, but not my first BMW. 20 years ago I had an R/90 with a documented 400k miles. It ran perfectly for the three years I owned it. Then about 10 years ago, I started riding G/s's. I had 3 r1150s of varying quality and loved them. But I started doing more intense dirt riding, and eventually sold my last one for a dual sport. Then I lost my job, and after a while, had to sell my dual sport too. For the first time in 27 years I was without a motorcycle. It was a tough year.

I've been picking up more work, and made the case to my wife that a project, if inexpensive enough, would be a good thing. I'd been trolling craigslist for months and this K75 kept haunting me. The problem with really cheap projects, is that the base bike at the end of it, is usually not very interesting. I came up on mid-70s hondas and had no desire to return. Most japanese bikes in my price range (less than $1500), were ugly, old, slow, beat to crap, and not worth my time.

But I've been brick-curious since they came out. So this seemed like a good way to get in to brick ownership without much risk. The bike, even if it didn't run, had enough parts to recoup my investment if it was totally dead. But since the PO had put 20k miles on it in 8 years without much trouble (he had kept a log book) before getting married and having kids, I was hoping it would just need a simple refresh before giving many more years of service. Pushing it around, the engine seemed to have compression, and it shifted through the gears.

So at the very end of the year I came home with a grubby '87 K75s with 96k on the clock, a progressive rear shock, a set of city bags, a set of the bigger bags, a tail-trunk, a stock seat and a corbin seat. He had bought it in 2004 for $1000 and did a lot of touring on it. The odo died in 2012 at 96,412, just before he stopped riding when his first daughter was born.Here's what it looked like before I washed it.

(https://photos.smugmug.com/Vehicles/BMW-K75s/i-63fpbTD/0/1704ad7f/XL/DSC_7274-XL.jpg)
(https://photos.smugmug.com/Vehicles/BMW-K75s/i-5KS4HKM/0/59d22e09/XL/DSC_7273-XL.jpg)
(https://photos.smugmug.com/Vehicles/BMW-K75s/i-zds7DKG/0/2af1174d/XL/DSC_7271-XL.jpg)

Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on January 08, 2018, 11:58:58 AM

I've owned a lot of project bikes over the years, and a good thorough bath is the first thing I always do. It lets me get familiar, and take notes on all the things I need to clean, replace, and investigate.


Once I washed it, I started stripping it down and hand cleaning the nooks and crannies.


My initial assessment:
All fluids in need of changing.
Wheels/Tires: good tread, but old, in need of replacement. No play felt in the bearings, both rotate freely without noise.
Brakes: non-operable due to lack of fluid. Rear master cylinder reservoir cracked and leaking due to UV.
Electrical: Unknown due to completely dead battery.
Tank: Gas cap hard to open, fuel pump gasket and in-tank hoses and proper clamps look to be in great shape. Slightly bubbled paint at the bottom corners revealed themselves to be several pin holes. At least partially resprayed at some point.
Rubber components: Replace. Fuel hoses cracked, vacuum hose cracked, crankcase breather badly cracked. Vacuum caps badly cracked, coolant tank sight hose discolored to the point of uselessness.
Wiring: Seemingly unmolested, and not too corroded at most of the connectors.
Body work: Poor. Both front turn signal lenses broken (one due to a crash, the other due to a ladder falling on the bike during an earthquake) Cracks in fiberglas, cracked windshield, center support bracket cracked around mounting bosses and barely attached.


(https://photos.smugmug.com/Vehicles/BMW-K75s/i-MLGwsN4/0/e2e8d279/XL/DSC_7281-XL.jpg)[size=78%]
(https://photos.smugmug.com/Vehicles/BMW-K75s/i-d9CdFVq/0/045f755b/XL/DSC_7289-XL.jpg)
(https://photos.smugmug.com/Vehicles/BMW-K75s/i-3BXGRWf/0/00d555e0/XL/DSC_7292-XL.jpg)[/size]
Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on January 08, 2018, 12:01:02 PM
Master Cylinder


(https://photos.smugmug.com/Vehicles/BMW-K75s/i-QfP5kcR/0/28adc139/XL/DSC_7295-XL.jpg)


Pump


(https://photos.smugmug.com/Vehicles/BMW-K75s/i-XFx2DPb/0/30ee6068/XL/DSC_7297-XL.jpg)


Pinholes


(https://photos.smugmug.com/Vehicles/BMW-K75s/i-9wFm6d7/0/95d36909/XL/image2-XL.jpg)



Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on January 08, 2018, 12:06:09 PM

My first step was to replace all the fluids. I started with the brakes. The front master cylinder was removed, cleaned in my harbor freight ultrasonic cleaner, and then refitted with fresh fluid. I got it to bleed quickly, and it built pressure, with the front calipers moving easily and not sticking on, but the MC leaked badly from the piston. Multiple removals, and gentle application of scotchbrite pads and 600 sandpaper to the bore didn't improve things. Luckily, my local cycle-salvage yard had 2 k75s! One C, one S. Picked up the whole throttle/switchgear/mc for $80. Cleaned it up, fitted it and the front brakes work well.


I changed the oil and filter (not too dark, no filings) and cleaned the oil off the bottom of the engine. No surprises, thankfully. I changed the transmission and final drive oil. There was a puffy halo of metal on the transmission magnet plug, but nothing large, it was essentially metal powder as I smeared it across a paper towel to check.


I removed and cleaned the airbox, put in a new airfilter. Removed the fuel rail, and cleaned the rust off of it. I removed the throttle bodies and cleaned them. I cleaned the ground wire for the battery, and the gang ground on the frame under the tank. Removed all the front body work, and replaced it temporarily with a standard headlight, and put the gauges on a piece of aluminum plate for now.
(https://photos.smugmug.com/Vehicles/BMW-K75s/i-fZ8Bdc7/1/93b986c2/X3/IMG_2760-X3.jpg)

I used some permatex epoxy to seal the pinholes, and replaced the fuel lines/vacuum lines/caps/etc..with some fresh gas the bike started, smoked for a while, but ran well as far as I can tell. I took it for a little cruise around my neighborhood and it shifted through the first three gears, ran smoothly, had decent power and stopped smoking. I was feeling pretty lucky so far. With it running, I started making a modified list of issues.



The low fuel light doesn't turn on (tested the bulb, it's ok). All the other lights seem to light appropriately, except I haven't checked the temperature light operation, the bulb works. The odometer doesn't work. I hope to get injectors cleaned and tested soon. The four-pin connector for the pump is a little flakey. I got a later model rear brake master cylinder from ebay. I'm waiting on a new fairing bracket from BMW. Turn signals will have to wait. The forks need to get new fluid, I'm waiting on an injection syringe from amazon today.


I put it back in the shop to pull the FD and take a look at the splines. The final drive spline/shaft is toast.  :musicboohoo:


(https://photos.smugmug.com/Vehicles/BMW-K75s/i-QmDKMZ9/0/6e72138b/X3/IMG_2783-X3.jpg)
Title: Re: '87 K75 Revival....maybe.
Post by: billday on January 08, 2018, 08:03:49 PM
Great posts, great pictures. Keep at it, and keep posting!
Title: '87 K75 Revival....maybe.
Post by: gofargogo on January 08, 2018, 08:51:34 PM
Thanks. I had plans, and parts to keep going with the refresh but the poor state of the splines has made me stop and consider my options.

I think, before I do anything else I need to pull the transmission and check the input splines. If those are toast as well, then I may be better off in parting out the bike than continuing to revive it.

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Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on January 09, 2018, 03:34:25 PM
So there was probably a tablespoon or two of rust colored gear oil in the driveshaft/spline area. Is that evidence of a bad seal? Also, resting the FD on the disc as I remember reading somewhere, has caused fresh gear oil to seep out and puddle on the disc. Is this coming from the vent? (Everything is currently filthy enough to make tracking down the seepage a problem. )


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Title: Re: '87 K75 Revival....maybe.
Post by: The Mighty Gryphon on January 09, 2018, 04:18:33 PM
My final drive leaked when set down on the disc.  It came from the vent.  You have to keep the final drive upright to not have it leak. 

Normally they don't leak into the swingarm.  I had to replace the input seal on my K75RT final drive.
Title: Re: '87 K75 Revival....maybe.
Post by: jakgieger on January 09, 2018, 06:40:07 PM
Good luck..if you need to finance your project, you could sell the city cases :bmwsmile !
Title: Re: '87 K75 Revival....maybe.
Post by: K1300S on January 09, 2018, 08:23:36 PM
keep at it!

saved a few K75S's...

Title: Re: '87 K75 Revival....maybe.
Post by: TaosBrick on January 10, 2018, 11:37:06 AM
Don't despair your FD/Driveshaft situation. When faced with the same thing on my '92 nekkid[size=78%] K75, I chose the to replace the whole bizness with an assembly from a first edition K100 which I found on eBay for a total of something around $200. The advantage to this setup is the 16 tooth spline arrangement, which I have been told is pretty much bulletproof, as opposed to the stock 22(?) tooth arrangement. The disadvantage, or additional advantage depending on how you look at it, is that the K100 FD is noticeably taller in ratio than the original. [/size]
[/size][size=78%]  My bike is in need of an injector cleaning, and the new setup makes things a bit more  sluggish, hoping getting 'em cleaned will improve that situation. as it is, I have to wring the piss out it while going up through the gears to make anything like reasonable acceleration happen. But then, a Klassic K of any stripe is not a crotch rocket by any stretch of the imagination. [/size]
[/size][size=78%]  The thing I DO like about the taller FD is lower revs cruising the slab at 80, which is where my whip spends many hours traveling cross country. [/size]
[/size][size=78%]  So I'd say just troll eBay til you find what you need. These bikes are real distance pigs, actually known to go 1,000,000 miles. Yours is a baby.  Good luck![/size]
Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on January 10, 2018, 11:50:32 AM
I’m pulling the tranny today to check the splines. If they are good, I’ll repair the fd/driveshaft and motor on. If they are bad, I’m considering doing a paralever mod to it. I mean, I’d need to buy a ton of parts off eBay anyway. With all the body work damage, and now the spline issues, the dark side of modding it calls to me. This isn’t a clean, unmolested example in the first place. But I often have wild flights of imagination for bike projects.


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Title: '87 K75 Revival....maybe.
Post by: gofargogo on January 10, 2018, 02:45:14 PM
Got the transmission pulled. The splines look ok to me. The flats across the tops are evident and not too beat up. There’s even evidence of some lube.

Judging by the mess, the rear main seal is leaking.
(https://uploads.tapatalk-cdn.com/20180110/1bdd1406e920798e879ebf939eb4c311.jpg)

(https://uploads.tapatalk-cdn.com/20180110/9bd54c598ffc8030472ab2a2366222d1.jpg)

It looks like the tranny output seal is leaking as well. I wonder if the gear oil coating the driveshaft is from that seal and not the final drive.

(https://uploads.tapatalk-cdn.com/20180110/a0d7de7f9102d165628145319cb46ed4.jpg)

The clutch/Spring plate is rusted and there’s moisture inside the clutch/flywheel area. I wonder why?

(https://uploads.tapatalk-cdn.com/20180110/e21cfbee3f66f462d2732b5540f301ff.jpg)


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Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on January 10, 2018, 03:37:03 PM
Reading back through the PO's maintenance notes. I'll give him credit, he took meticulous notes during his tenure. He replaced the clutch and seal at 85k, 11 years ago. It has somewhere north of 96k now. It's possible he didn't clean out the housing and the oil residue I'm seeing is just the remnants from then. I'm thinking that if it was still leaking, the clutch basket would not be rusty, but covered with oil residue, am I wrong?
Title: Re: '87 K75 Revival....maybe.
Post by: John Lang on January 10, 2018, 04:21:26 PM
Rust-colored muck in the FD/Driveshaft area is probably Staburags moly paste flung off the rear splines. Normal, and good news.
Title: Re: '87 K75 Revival....maybe.
Post by: The Mighty Gryphon on January 10, 2018, 05:45:05 PM
Leakage at output shaft is probably the clutch o-ring.  They harden over time.  The seal is less likely, especially since it only has 11,000 miles on it.
Title: Re: '87 K75 Revival....maybe.
Post by: rbm on January 10, 2018, 06:05:40 PM
The main seal could leak if it was replaced flush with the housing, instead of 0.5mm proud.  It would ride in the same spot as the old seal and wouldn't do its job.  This was an install instruction from BMW.
Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on January 10, 2018, 08:54:47 PM
I cleaned everything up, and will check it again when I replace my driveshaft/FD. It's not that much more work to get the gearbox out. I decided that if there's a problem I'll replace the seal and oring then.
Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on January 13, 2018, 07:39:35 PM
After traveling for work for a couple of days, I woke up and decided to tear apart the front end for servicing. I knew the head bearings were stiff, and the fork oil was an unknown.
The head bearings were totally gunked up with hardened grease, but the races were in tolerable shape. I decided to service them and she how good I could get them before spending the money on new bearings. 20 minutes of soaking in mineral spirits, some scrubbing with a brass brush before an hour in my ultrasonic cleaner and they came out sparkling and free. I didn’t see any pitting or discoloration on the rollers, so I packed them with grease and reinstalled them. Side to side movement of the triple clamps was smooth and easy now, with no discernible notching or hang ups.
The forks got removed, drained (of nasty black fluid) and refilled with atf. I’ll ride that for a couple hundred miles and then drain and refill again.


I took the opportunity to to replace the cracking fork seal protectors with rancho gaiters. Cheap, and they fit really well. One of the seals may be leaking a little, but I’ll ride it and see if it improves.


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Title: Re: '87 K75 Revival....maybe.
Post by: Martin on January 14, 2018, 12:30:52 AM
Seals can sometimes be made to seal with a Seal Mate. These can be bought or made using a soft drink bottle. Look it up and copy it by cutting out of the bottle, shape is not super critical. And external soak with a rag soaked in ATF wrapped around them for a few days also helps.
Regards Martin.
Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on January 14, 2018, 12:34:58 AM
I rode it about 20 miles today running around the area. I love the sounds and smoothness of the motor!


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Title: Re: '87 K75 Revival....maybe.
Post by: K1300S on January 14, 2018, 08:45:11 AM
Working fast!   Nice!
Title: Re: '87 K75 Revival....maybe.
Post by: The Mighty Gryphon on January 14, 2018, 09:18:21 AM
hooked another one...
Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on January 14, 2018, 12:11:00 PM
Advice for those looking at bricks: be patient and buy one that hasn’t been sitting unless you get it for next to nothing. These bikes really don’t like to sit.

Good, clean running examples are shockingly cheap for what you get. There’s no reason to buy an orphan unless you really like combing through every part of a bike and fixing neglect.


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Title: Re: '87 K75 Revival....maybe.
Post by: billday on January 14, 2018, 04:17:40 PM
Man, have you drunk the Kool-Aid or what?

Welcome to the club!
Title: '87 K75 Revival....maybe.
Post by: gofargogo 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’m pretty sure I’m  missing hardware.

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Title: Re: '87 K75 Revival....maybe.
Post by: The Mighty Gryphon 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.
Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on January 15, 2018, 03:45:56 PM
I’m pretty sure I’m 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.

(https://uploads.tapatalk-cdn.com/20180115/100ee6744a662cde3947c78aefec595b.jpg)


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Title: Re: '87 K75 Revival....maybe.
Post by: Laitch on January 15, 2018, 05:34:05 PM
I’m pretty sure I’m 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.

(http://www.motobrick.com/gallery/0/1601-150118172634.jpeg)

(http://www.motobrick.com/gallery/0/1601-150118172715.png)
From MAX BMW'S parts fiche.
Title: Re: '87 K75 Revival....maybe.
Post by: Martin 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.
Title: Re: '87 K75 Revival....maybe.
Post by: TaosBrick 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.
Title: Re: '87 K75 Revival....maybe.
Post by: Laitch on January 15, 2018, 11:12:01 PM
Here is a more explanatory photo.

(http://www.motobrick.com/gallery/0/1601-150118231046.jpeg)
Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo 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’t have any problem cutting and rewelding the shaft.


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Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on January 15, 2018, 11:15:09 PM
Here is a more explanatory photo.

(http://www.motobrick.com/gallery/0/1601-150118231046.jpeg)
Thank you. This helps a lot. I have everything but the stay (and clips)


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Title: Re: '87 K75 Revival....maybe.
Post by: Martin 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.
Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on January 16, 2018, 01:17:05 AM
I was thinking about a length of bicycle chain...


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Title: Re: '87 K75 Revival....maybe.
Post by: Laitch on January 16, 2018, 01:35:11 AM
I'm thinking of a number between one and ten.
Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on January 16, 2018, 01:42:21 AM
I'm thinking of a number between one and ten.
7.5?


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Title: Re: '87 K75 Revival....maybe.
Post by: TaosBrick 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’t have any problem cutting and rewelding the shaft.


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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.
Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo 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.
Title: Re: '87 K75 Revival....maybe.
Post by: Laitch 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.
Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo 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.
Title: Re: '87 K75 Revival....maybe.
Post by: Laitch 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?
Title: '87 K75 Revival....maybe.
Post by: gofargogo 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.


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Title: Re: '87 K75 Revival....maybe.
Post by: Martin 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.
Title: Re: '87 K75 Revival....maybe.
Post by: Skunky 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
Title: Re: '87 K75 Revival....maybe.
Post by: riots100 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.
Title: Re: '87 K75 Revival....maybe.
Post by: Filmcamera 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.
Title: Re: '87 K75 Revival....maybe.
Post by: The Mighty Gryphon on January 18, 2018, 08:39:13 AM
Have you drained the trsansmission oil since this problem started?  What does it look like?
Title: Re: '87 K75 Revival....maybe.
Post by: TaosBrick 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.
Title: Re: '87 K75 Revival....maybe.
Post by: Rcgreaves on January 18, 2018, 05:46:40 PM
Hook Line Sinker.  Excellent! :clap:
Title: '87 K75 Revival....maybe.
Post by: gofargogo on January 19, 2018, 03:10:19 PM
Did another short Test ride around the neighborhood to see if maybe my clutch cable was stretched and not letting it fully engage and disengage the clutch, thus not allowing a good solid shift into 2nd.

The ride proved that the problem remains. So, since my final drive, my driveshaft and my tranny need to replaced, is there any reason (besides keeping it stock) to NOT replace everything with k1100 paralever parts?
Besides having to buy the paralever arm, and new shock, it seems like it’s roughly the same cost for eBay parts.


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Title: Re: '87 K75 Revival....maybe.
Post by: rbm on January 19, 2018, 09:15:36 PM
No reason not to, and you'll enjoy the improved ride as well.
Title: Re: '87 K75 Revival....maybe.
Post by: TaosBrick on January 20, 2018, 01:05:06 AM
No reason not to, and you'll enjoy the improved ride as well.
Second that!
Title: Re: '87 K75 Revival....maybe.
Post by: The Mighty Gryphon on January 20, 2018, 08:29:31 AM
You'll be able to use radials on the back with a wider rim.
Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on January 21, 2018, 12:10:04 PM
Yeah, I’m pricing three spoke wheels too. But in the short term, I can run my y-spoke wheel on the k1100 final drive?


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Title: Re: '87 K75 Revival....maybe.
Post by: The Mighty Gryphon on January 21, 2018, 08:26:25 PM
No problem, classic brick wheels are interchangeable as long as the tire you mount doesn't hit the swingarm.  A former member here, Frankenduck, has put Paralevers and K1100RS rims on K75's.
Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on January 22, 2018, 01:09:48 AM
Awesome. Thank you.


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Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on January 28, 2018, 11:16:44 PM
Update: sourced a k1100 transmission and I’m in the process of installing it. God, getting to the splines goes so much faster the second time.

Here’s hoping it’s not broken as well.


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Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on January 30, 2018, 02:15:04 PM
The transmission works well, shift smoother than the old one too.
I’m still running the mono lever shaft and final drive until my eBay parts show up.
And I’m still sourcing parts to make it back into an “s” but I’m enjoying the naked bike experience again. It’s been a while.
(https://uploads.tapatalk-cdn.com/20180130/f6cb7f9e864dafd1229e3342ecd6aae4.jpg)


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Title: Re: '87 K75 Revival....maybe.
Post by: TaosBrick on January 30, 2018, 11:39:09 PM
Saw both an '85 K100 16 tooth FD and Driveshaft in good shape on fleabay, cost ya about $500 total. Got my setup for a good bit less than half of that. Good things come to those who wait...
Title: Re: '87 K75 Revival....maybe.
Post by: Skunky on February 02, 2018, 04:28:57 PM
Loving the tea cup holder built into the tragkorb  :hehehe
Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on February 02, 2018, 04:31:10 PM
It’s not proper shop time without the cup of tea.


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Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on April 11, 2018, 09:49:28 PM
I finally got enough parts to reinstall the fairing today and took it for a 10m freeway ride. Wow, this is is really nice! I think there's a bit more noise in my helmet, but no buffeting, at least compared to what I'm used to. I could really eat up some miles with this setup. I guess that means I should start fixing all the little things since I'll be keeping the bike. It's really amazing to me that this bike is 31 years old. I mean, my particular example is a bit flogged, but the sophistication of this thing must've been mind blowing in 1987.


I'm still running on my bad splines, probably 1500 miles since I purchased it but I know it's borrowed time.
Title: Re: '87 K75 Revival....maybe.
Post by: The Mighty Gryphon on April 12, 2018, 01:00:25 AM
Sounds like you are making some progress. :clap:
Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on April 13, 2018, 04:59:30 PM
Getting there! Now I need to take by an autobody shop and see how much they'll charge to get the fairing fixed and painted at least.


Does anyone have good photos of how the wiring harness is routed in front of the forks? I neglected to photograph that when I pulled it apart and now I can't remember how it's supposed to go. :( I've done a google search but didn't find anything detailing anything beyond what happens under the tank.


And how do classifieds work here? I can't see any threads and I've been on the hunt for a left front turn signal for ages.
Title: Re: '87 K75 Revival....maybe.
Post by: Laitch on April 13, 2018, 05:10:04 PM
Hey, how do classifieds work here? I can't see any threads and I've been on the hunt for a left front turn signal for ages.
Go up the menu to the Motobrick Marketplace to the FS-WTB-WTT section. The Classifieds Section isn't open yet. Maybe by Black Friday. :giggles
Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on April 13, 2018, 05:12:40 PM
Go up the menu to the Motobrick Marketplace to the FS-WTB-WTT section. The Classifieds Section isn't open yet. Maybe by Black Friday. :giggles

Thank you. I never would've found that.
Title: Re: '87 K75 Revival....maybe.
Post by: TaosBrick on April 15, 2018, 05:55:29 PM
If you google "1987 K75 Wiring Diagram", a bunch of possibilities come up, mostly black and white. If you search a bit harder you may find a colour one. All Chilton's manuals come with full colour wiring diagrams.
Title: Re: '87 K75 Revival....maybe.
Post by: The Mighty Gryphon on April 15, 2018, 10:51:53 PM
I'm pretty sure you can get the turn signal for a K75S from BMW.  I bought one just last November.
Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on April 16, 2018, 01:22:59 AM
I'm pretty sure you can get the turn signal for a K75S from BMW.  I bought one just last November.
For almost 25% of my bikes purchase price! (I’ll stop cheaping out on parts eventually...)


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Title: Re: '87 K75 Revival....maybe.
Post by: Laitch on April 16, 2018, 08:11:45 AM
For almost 25% of my bikes purchase price! (I’ll stop cheaping out on parts eventually...)
You found an extraordinary bargain and now everything has to be a bargain for you.  That's overreaching and the gateway to bad juju.

It's a fine looking machine though.  :2thumbup:
Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on April 17, 2018, 03:05:54 PM
You found an extraordinary bargain and now everything has to be a bargain for you.  That's overreaching and the gateway to bad juju.

It's a fine looking machine though.  :2thumbup:


Fair point. Some of it is my inherent cheapness, some of it is aesthetics. The right turn signal is in good shape, but not new, and the rears are both pretty aged. One brand new turn signal upsets my sense of balance. I've spent a bit of money on the mechanical side of things, and will continue to do so. It's close to being mechanically sound, so I need to start repairing the more aesthetic parts.


My goal now is to sloooooowly fix and refresh every part of the bike. Slowly because I'm on a tight budget, and because it's in that dangerous phase where it's ridable and the weather is good. I'm going to delay some of the bigger portions until the winter (such as getting the body work fixed).



Title: Re: '87 K75 Revival....maybe.
Post by: gofargogo on June 21, 2018, 11:08:41 AM
Between A&S and eBay, I now have all the turn signals, and the bike is “complete” from a parts perspective. The turn signals worked for 3 days before going dead, I fear that the flasher gave up the ghost but haven’t pulled the tank to check, I’ve been too busy riding it.

These are neat bikes. [emoji3]


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