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MOTOBRICK.COM => Welcome To Motobrick.Com => Topic started by: Adam M on July 11, 2018, 08:14:43 PM

Title: Starting the research on R80 and K75
Post by: Adam M on July 11, 2018, 08:14:43 PM
After a month spent in Europe on slightly modified R80 I decided to research it together with K75.
My Triumph T150V rides great, unfortunately my body feels quite beaten up after a ride longer than 100 km.
I know I could improved it further by installing better front end with better brakes, better rear shocks, but don't want to mess with original bike.
So probably has to sell it in a year or two and go a BMW route.
Only problem I see with BMW, I'm short ( 173 cm tall ) so my first question is how high K75 is ?
I was OK with R80, but it's seat was lowered.
Another question, could somebody compare both bikes ?

Thank you.
Ah, I'm from Mississauga, Ontario.
Title: Re: Starting the research on R80 and K75
Post by: Laitch on July 11, 2018, 08:39:51 PM
I'm short ( 173 cm tall ) so my first question is how high K75 is ?
K75 models came in a standard seat version or a low seat version. The low seat is 760mm high. It has a profile and seat components distinct from the standard seat. The red bike is a low seat version. The arrows show its unique tank pad and how the seat has a sloping profile. The low seat is not hinged; it can be slid off to access the battery.
(http://www.motobrick.com/gallery/1/1601-110718203536.png)

The black bike has a standard seat. The seat is 810mm high. The arrows show its horizontal profile and its battery cover which is not present on the low seat model. The standard seat is hinged for access to a small tool box and the battery beneath the tool box.
(http://www.motobrick.com/gallery/1/1601-110718203827.png)
Title: Re: Starting the research on R80 and K75
Post by: Martin on July 11, 2018, 09:05:21 PM
 Go here to compare http://cycle-ergo.com/. You can also have the seat nose shaved or the whole seat lowered by a competent upholsterer experienced with motorcycle seats. You can buy motorcycle boots with the thickest soles available, they can vary in thickness by up to 1. You can add lifts to the boots, if doing both buy the lifts first to try in the boots as some boots wont accept lifts. Doing both will increase your height by 2"+.You can drop the forks through the trees by 1/2" without noticeable effects on the handling. There is a shorter rear shock available but it can effect clearance and it will be harder to get onto the centre stand. The stand can be shortened to suit. I am 1" shorter than you and with a Jo foamed lowered seat and thick soled motorcycle boots I can flat foot with slightly bent knees.

Regards Martin.
Title: Re: Starting the research on R80 and K75
Post by: Chaos on July 11, 2018, 11:42:56 PM
Hard to compare an r80 and a k75.  The r has more character but is more fiddly with carbs and valve adjustments.  The k is smoother and feels more top heavy.  Both are great bikes, I could live with either. 
Title: Re: Starting the research on R80 and K75
Post by: Martin on July 12, 2018, 01:53:43 AM
When I first started looking for a bike, a couple of mates with Hardleys tried to talk me into one. :hehehe I looked at Guzzi's before looking at BM's. I used to have a work colleague that had a R90s that I drooled over. So after talking to a guy I worked with who was an Ex BM Hardley tech his advice was to go for a BM. I was looking at R80's he told me to have a look at K75's. I still love the look of the R80 especially with a bikini fairing.
Regards Martin.
Title: Re: Starting the research on R80 and K75
Post by: blackie1 on July 12, 2018, 03:37:34 AM
hi Adam m
i have owned both and if forced to choose then my personal preference would be the k75 all day long.
smoother, accelerates quicker and more nimble than the R80
the R80's sheer simplicity  and ease of accessibility however beats the K75 which is a bit more complex with the fuel injection.
flip a coin
everyone's a winner baby
 :2thumbup:
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 12, 2018, 08:56:19 AM
K75 is also much cheaper in my area, but not many of them show up.
After 15 years with old british bikes, carbs are not fiddly to me at all :), however K's fuel injection would be a think to master.
From what I read on the forum engine is pretty much unburstable, gearbox, shaft and final drive are R80 parts anyway.
I thought about K because I like triples, and liquid cooling makes engine temperature more stable.
With Triumph during a hot day I start with cold engine and very slow idle to have a racing engine on idle after some traffic jams in town.
But inevitably the cooling and FI makes it much more complicated comparing to R80, which is as reliable, simple enough for me to do not only maintenance but all the possible repairs by myself and is not affected by heat at all. A month ago I was riding through Berlin in 30C degrees days without any problems.
Title: Re: Starting the research on R80 and K75
Post by: Chaos on July 12, 2018, 09:07:57 AM
r80/r100 beats the K75 as far as simplicity, but in 200k I have never touched the FI on mine except to replace aging fuel lines.  And I've only checked the valves about 4 times, changed shims on 3 or 4 of them.  Biggest issue might be price, R's seem closer to having a collector's mystique than K's. 
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 12, 2018, 10:10:52 AM
Perhaps you should clean injectors ? :).
On the different note is your Dnepr side valve ?
Title: Re: Starting the research on R80 and K75
Post by: Chaos on July 12, 2018, 11:17:19 AM
Perhaps you should clean injectors ? :).
On the different note is your Dnepr side valve ?
Haha, Techron seems to do the trick.  And no, it's a Ural with overhead valves, similar to a /2 with the pushrod tubes above the cylinders. 
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 12, 2018, 11:33:20 AM
Aha, I had a close encounter with such a machine 10 years ago, helped a friend to cure a hole in one piston and installed electronic ignition in it.
It changed a bike a bit with much easier starting and even idle. However his was an older Ukrainian home market model.
I also believe you use an old picture of my polish virtual friend working on her K750 :).
Title: Re: Starting the research on R80 and K75
Post by: Gibson on July 12, 2018, 11:34:10 AM
I have a r100r Mystic and a K75 both 94 models. I also rode a 92 r100r for about 25k miles. I've been riding the K75 every day now. The R100 is much lighter maybe by 100 lbs. My R100M is a smaller bike. The seat is lower it handles better and has much better front brake setup and better rear suspension than the K. The K bike shifts better, starts easier, is smoother, has clock and gear position indicator, no charging issues, no fuel petcocks, no overheating in traffic etc. It appears that BMW attempted (and very successfully so) to solve some of the shortcomings with the Rs. I love the R bikes for its simplicity and charm. I don't think you can go wrong with either.
Title: Re: Starting the research on R80 and K75
Post by: Laitch on July 12, 2018, 11:53:16 AM
. . .  it's a Ural with overhead valves, similar to a /2 with the pushrod tubes above the cylinders.
Doesn't it also have an oil filter instead of an oil slinger—as a nod to evolution? :giggles
Title: Re: Starting the research on R80 and K75
Post by: Chaos on July 12, 2018, 12:24:26 PM
actually it has both, very low pressure pump (3-5 psi) with filter and a slinger for what doesn't get splashed or dripped on.  And yes, I stole that avatar because she is just too damn gorgeous!
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 12, 2018, 04:43:02 PM
How can I edit posts ?
I made a mess in another thread, trying to insert a picture from postimage.org and don't see any edit button around a post body ?
Title: Re: Starting the research on R80 and K75
Post by: Laitch on July 12, 2018, 05:18:13 PM
How can I edit posts ?
I made a mess in another thread, trying to insert a picture from postimage.org and don't see any edit button around a post body ?
There are a couple of images of a bike in one of your threads. We don't get modify buttons right off the bat so you should carefully Preview your posts until you get one. We'll all just live with your messes until you have means to clean them up. :giggles
Title: Re: Starting the research on R80 and K75
Post by: Laitch on July 12, 2018, 06:01:30 PM
. . . however K's fuel injection would be a think to master.
The thing about the L-Jetronic system on a K75 is that there is nothing to master so you don't need to think about it; however, if you buy a clapped-out, neglected, used K-bike what you'll need to master is electronic diagnosis using a multi-meter so you can go through all the Jetronic functions to determine if the ohms and voltage are at spec, only to find out that what you should have done is replaced the fuel filter and fuel hoses. :giggles
Title: Re: Starting the research on R80 and K75
Post by: Gibson on July 12, 2018, 06:09:08 PM
Fuel injection on these bikes is very basic by today's standards, but it works very well. These bikes are as easy to work on as the R but a bit more technical. I have been riding R bikes for 40 years but enjoy working on the K
Title: Re: Starting the research on R80 and K75
Post by: stokester on July 12, 2018, 06:41:18 PM
Fuel injection on these bikes is very basic by today's standards, but it works very well. These bikes are as easy to work on as the R but a bit more technical. I have been riding R bikes for 40 years but enjoy working on the K
Same here, I've been able to do all the diagnosis, work, and certainly all the maintenance so far on both types of BMWs following advice found here and other online forums.  The extra complication of fuel injection is a non-issue to me with only the fuel pump, filter, lines and injectors added to the mix.  I'm sure it has failed on some but the control module appears to be pretty robust.  After all I'm sure all of us depend on these systems in our daily drivers.

The most complex thing I diagnosed was the ABS and using on-line references and analog meter I was able to get the brain fixed by Tosi in Japan.
Title: Re: Starting the research on R80 and K75
Post by: Gibson on July 13, 2018, 07:16:21 AM
I think the K75 makes an ideal daily commuting machine. So care free and easy. It appears convenience was important in this design. If it was only a bit lighter...but then it wouldn't ride like it does I guess. I ride the K every day to work and love it. I feel like I've been missing out on some very cool machines this whole time. :riding:
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 13, 2018, 07:39:34 AM
What's the weight of K ?
How easy / hard is to place it on a center stand ?
Title: Re: Starting the research on R80 and K75
Post by: Laitch on July 13, 2018, 09:30:02 AM
What's the weight of K ?
How easy / hard is to place it on a center stand ?
The weight of a naked K75 is approximately 500lbs. Go to the following site for all points of comparison among most BMW motorcycles. http://www.bmbikes.co.uk/bmwmodels.htm (http://www.bmbikes.co.uk/bmwmodels.htm)

It will be difficult for you to place it on the side stand if you have poor abdominal core strength and weak leg muscles.
Title: Re: Starting the research on R80 and K75
Post by: Gibson on July 13, 2018, 09:46:38 AM
If you use the right technique it is about the same as my R100 (not bad at all). The K has a conveniently located grab handle that folds out above the left foot rest. If you use that, and focus on stomping down as you lift it, its not bad at all. I always center stand both bikes. Very important on R bikes, not sure yet with k.   
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 13, 2018, 10:38:24 PM
I'm dangerously close to 70, but still squat with some 100 something lbs on my back and dead lift the same.
So leg muscle and core are still there. :)
Also can still put my Trident on the center stand, what could give a hernia to a young man. It's weight is 500 lbs too, but stand is bloody difficult.
Laitch, thanks for another great source, Gibson - K bikes have to be center stand too. Left on the prop stand they tend to smoke.
Title: Re: Starting the research on R80 and K75
Post by: Chaos on July 14, 2018, 08:46:35 AM
after decades of using the centerstand I've relegated it now pretty much just for maintenance use.  Stories of it collapsing and general laziness are the culprits.  Two tricks to using the sidestand, tilt the bike to the right for a moment after shutting it off, and before starting it back it out of it's spot so you can drop it into gear and have a clean getaway, avoiding the glares and criticisms of onlookers and they succumb to a cloud of K smoke.  Actually, mine only smokes maybe 1 out of 10 times, no rhyme or reason.   :dunno
Title: Re: Starting the research on R80 and K75
Post by: The Mighty Gryphon on July 14, 2018, 10:04:28 AM
Why be ashamed of K-smoke.  That cloud of oil mist wafting gently downwind is providing a nano film of rust preventative to anything it envelopes.  Not to mention the flying insect control.

You are doing a public service... 
Title: Re: Starting the research on R80 and K75
Post by: stokester on July 14, 2018, 12:34:51 PM
after decades of using the centerstand I've relegated it now pretty much just for maintenance use.  Stories of it collapsing and general laziness are the culprits.  Two tricks to using the sidestand, tilt the bike to the right for a moment after shutting it off, and before starting it back it out of it's spot so you can drop it into gear and have a clean getaway, avoiding the glares and criticisms of onlookers and they succumb to a cloud of K smoke.  Actually, mine only smokes maybe 1 out of 10 times, no rhyme or reason.   :dunno
Me too.  I feel the bike is more stable on the sidestand after finding my K75 sunk into the asphalt up to the foot pad when using the centerstand.  I always carry a pad for the sidestand to prevent that sinking feeling on questionable surfaces.

It smokes on startup about the same frequency as my airheads which is not very often but when it does there always seems to be an audience  :mbird
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 14, 2018, 03:24:18 PM
I took a look at very nice 92 K75S this afternoon, had an opportunity to seat on it and put it on the center stand.
I didn't ride because of constant rain. No problem at all with center stand it, I can do it in my sandals easily.
I checked the bike quite extensively and it looks very well taken care for. Only problem I see is original position with very short handlebar which is placed too far forward to my liking. Current owner told me I can use some kit to rise it a bit and place it back, without changing a length of a brake hose.
Did anybody used it and with what result ?
Title: Re: Starting the research on R80 and K75
Post by: Chaos on July 14, 2018, 04:12:05 PM
I've have the barbacks he's referring to, that little bit up and back made a huge difference to me.  Usually the brake line will be fine. Search ebay and vendors   https://www.panjo.com/buy/handlebar-riser-bar-backs-for-k75-k100-bmws-197854
Title: Re: Starting the research on R80 and K75
Post by: stokester on July 14, 2018, 04:30:21 PM
<SNIP>
Only problem I see is original position with very short handlebar which is placed too far forward to my liking. Current owner told me I can use some kit to rise it a bit and place it back, without changing a length of a brake hose.
Did anybody used it and with what result ?
I find the K75S ergonomics near perfect for my nearly 6' frame and long arms but know that it is too far forward for many.

There will probably be others who chime in that the handlebars from a K75C meet the need.
Title: Re: Starting the research on R80 and K75
Post by: blackie1 on July 14, 2018, 05:14:31 PM
don't worry about the handle bar position, after all you have only sat on it for wat... a minute.
anything new to you will feel different.
ride it for a month and it will fit u like an old glove. humans have been adapting for millenia, although some would say the aussies have timed out on their adaptation duties.

of course i would never say that
 :clap:
Title: Re: Starting the research on R80 and K75
Post by: Martin on July 14, 2018, 05:28:08 PM
Before buying new bars try adjusting them, as you rotate them back they also come up. I've adjusted mine progressively over the years. The last modification involved spacers moving the bars up 1" and back 1".

Regards Martin.
Title: Re: Starting the research on R80 and K75
Post by: blackie1 on July 14, 2018, 05:55:08 PM
martin i am shattered i could not get a rise out of u lol
Title: Re: Starting the research on R80 and K75
Post by: rbm on July 14, 2018, 06:18:11 PM
Contact me, Adam, if you want me to accompany you to do a once-over.  Hopefully it's not in Kanata or London or somewhere else well outside the GTA. :)
Title: Re: Starting the research on R80 and K75
Post by: Martin on July 14, 2018, 06:24:50 PM
Blackie since I have now retired nothing that mild will get a rise out of me. I could make a crack about Kiwis, but it would be too easy and be a cheap shot. :neener:
Regards a totally cooled out Martin.
Title: Re: Starting the research on R80 and K75
Post by: duckhawk on July 14, 2018, 11:09:52 PM
I have owned both. I had an 81 R80RT.

 [ Invalid Attachment ]


The R80RT was truly an amazing bike. The ergonomics were perfect for me. It was so perfectly balanced I could ride no handed and, lean only, on long radius turns for literally miles at a time.

I had to sell it to get the 02 1150 and I sold it for more than I paid for it.

The boxer engine was not smooth at low RPMS and shook the bike when lugged, but sang at 50-80mph. The tranny was unforgiving and took a while to master. Compared to the sewing machine precision of the K75's engine and gearbox, the R80's engine was clunky. The 1150's is the same way. 2 pistons mashing out brute force power when stomped on. Nothing like the steady roll on of the K75 , at any rate.

Once, after not checking the tire pressure, I bounced  the R80 hard off a curb on a left turn, AND IT BOUNCED ME BACK ON THE ROAD. After that day I swore I would own nothing but a boxer.

In contrast, another time I wound it hard up the gears while touring in a rain storm and it popped out of gear between 4th and 5th at 80MPH and scared the hell out of me.

Bottom line, the low center of gravity was a complete joy, saved me once, and that's why I own the 1150.


The K75 is different. I bought it, sight unseen, and flew out to the Carolinas and rode it back to Wisconsin in 2 days of super-slab riding. It took me a while, but after the used scout fairing, I found myself riding it 80% of the time. Mostly because of the smoothness, less weight, less shifting with the expansive powerband. It is my CITYBIKE.

Now, I am training my son to ride. He is an amateur dirtbiker, so he has some riding skill, but I trust the K75's smoothness and steadiness to help him along.

Wrenching. To me it takes the same skill level to do both bikes. I have always adjusted my own valves, basic maintenance, etc. Vintage dirtbike maintenance is simplistic compared to these roadbikes. But with all the info the sites like this, you can learn to do most of the non-major stuff.


Why buy one, when you can buy two for twice the price!!
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 14, 2018, 11:16:23 PM
Hi rbm it's in Newmarket, I wouldn't feel well to pull you all the way there.
I plan to go there on my bike, to try it as long as my body remembers the last BMW :).
The current owner is very particular, he has all recites and hand written blog of anything done to the bike over the years.
Title: Re: Starting the research on R80 and K75
Post by: Skunky on July 15, 2018, 07:43:16 PM
 [ Invalid Attachment ]   :hehehe
Title: Re: Starting the research on R80 and K75
Post by: bocutter Ed on July 16, 2018, 10:34:38 AM
it's in Newmarket
That's only an hour North of us not taking the slab. I'll go here www.milbreeviking.com for a doughnut ...
Title: Re: Starting the research on R80 and K75
Post by: Martin on July 16, 2018, 03:20:38 PM
Arhhhhh, Donuts. :lets-eat:
Title: Re: Starting the research on R80 and K75
Post by: bocutter Ed on July 16, 2018, 03:39:15 PM
Arhhhhh, Donuts. :lets-eat:
This bakery also makes ground meat filled donuts (no sugar in the dough).  :lets-eat:
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 16, 2018, 03:57:50 PM
I'll take it under consideration, however this bakery is closed until July 18.
Title: Re: Starting the research on R80 and K75
Post by: bocutter Ed on July 16, 2018, 04:10:26 PM
Yup, reopens Thursday. I have a Ride Leader training session at noon Thursday.
Title: Re: Starting the research on R80 and K75
Post by: Martin on July 16, 2018, 04:11:08 PM
Ed Why that's like putting ground beef in a chocolate éclair. :nono :musicboohoo:
Regards Martin.
Title: Re: Starting the research on R80 and K75
Post by: bocutter Ed on July 16, 2018, 04:55:01 PM
Nah, it's more like a sausage roll, sans the flakey pastry, stuffed in a savory donut. Once I went in for a fruit donut and Liisa the baker had made them with the 'other' dough = half price.

I remember having an éclair at Harrods when I was a child. Asked Granny if I could have another, ever so politely ... yesss!
Title: Re: Starting the research on R80 and K75
Post by: bocutter Ed on July 16, 2018, 04:58:43 PM
[ Invalid Attachment ]   :hehehe
Woodn't those boots be an impediment to being shifty.
Title: Re: Starting the research on R80 and K75
Post by: Martin on July 16, 2018, 05:06:11 PM
Ed Beefy's pies make the best eclairs ever, proper chocolate, cream filled we have two 5 min in either direction. :lets-eat:
Regards Martin
 [ Invalid Attachment ]
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 17, 2018, 08:26:31 PM
Two more questions.
The bike I'm going to see tomorrow ( 92 K 75S ) doesn't have an ABS. Pumps are removed by the previous owner.
What can I expect from ABS lamp ?
What is minimal thickness of rotors ?
This bike has 3 of them and front ones look pretty thin to me.
Title: Re: Starting the research on R80 and K75
Post by: rbm on July 17, 2018, 08:55:06 PM
If the ABS is completely removed, that should include the ABS brain located in the tail compartment.  The ABS light should be extinguished if so.

The minimum brake disk thickness is 3.6mm.  I believe a new disk is 4.5mm (taking a guess here).

Update:  Looked it up. A new disk is  4.0mm
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 17, 2018, 09:11:11 PM
Thanks rbm.
I'm used to around 5 mm in old Japanese bikes.
Title: Re: Starting the research on R80 and K75
Post by: blackie1 on July 18, 2018, 02:57:49 AM
brake pads are cheap and easy to replace
Title: Re: Starting the research on R80 and K75
Post by: Chaos on July 18, 2018, 09:39:30 AM
mine got down to 3.3mm  :yow
Title: Re: Starting the research on R80 and K75
Post by: Gibson on July 18, 2018, 09:52:24 AM
Yep 4mm. How many miles on it? Rotors should be good for 70-80K miles or more.
Title: Re: Starting the research on R80 and K75
Post by: johnny on July 18, 2018, 10:07:51 AM
greetings...

i took my motoheap to a socal dealer for their $30 oil change and moto warsh...

after i paid they told me they could not release my brick to me eithout new disks because my disks were at 2.5mm and not roadworthy...

i caught a ride to fetch my spare key... returned and stole my own moto...

those disks are 2mm now and brake like a moe...

f the booshee and ride...

j o
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 18, 2018, 10:10:54 AM
Another question, were electronic circuit board is located ?
Have impression that it was deleted too.
Bike has 80k km on it, but could be 180 k as well.
However current owner looks trustworthy to me and bike looks very good and in constant use.
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 18, 2018, 10:13:11 AM
John, I'll use your advice when bike is in my possession during the weekend :).
Title: Re: Starting the research on R80 and K75
Post by: Gibson on July 18, 2018, 10:24:07 AM
No doubt you need rotors with that crack, :nono looks dangerous....
Title: Re: Starting the research on R80 and K75
Post by: Chaos on July 18, 2018, 12:35:09 PM
Yep 4mm. How many miles on it? Rotors should be good for 70-80K miles or more.

Those were my 2nd set, both went about 95k, replaced them with EBC rotors this time around. 
Title: Re: Starting the research on R80 and K75
Post by: Chaos on July 18, 2018, 12:49:51 PM
greetings...

i took my motoheap to a socal dealer for their $30 oil change and moto warsh...

j o

$30  ool change from a dealer?  Hell, that's a ploy to get you in there so they can riffle through you saddlebags and find incriminating evidence to extort $3875 tune up from you :deal:
Title: Re: Starting the research on R80 and K75
Post by: rbm on July 18, 2018, 03:42:32 PM
Another question, were electronic circuit board is located ?
Which circuit boards are you referring?  If its the ABS, the circuits are in the tail of the bike.
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 18, 2018, 03:47:50 PM
The board controlling all the lights, blinkers and tells you a bulb is broken :).
Title: Re: Starting the research on R80 and K75
Post by: Laitch on July 18, 2018, 03:59:07 PM
Bike has 80k km on it, but could be 180 k as well.
It could be, but if it has been operating accurately, its odometer should read something like 080000. The main odometer on classic K-bike Motometers records miles/kilometers six places left of decimal.
Title: Re: Starting the research on R80 and K75
Post by: Gibson on July 18, 2018, 04:10:35 PM
I still have 2 zeros all the way to the left. I have a way to go I guess... :riding:
Title: Re: Starting the research on R80 and K75
Post by: rbm on July 18, 2018, 04:39:02 PM
The board controlling all the lights, blinkers and tells you a bulb is broken :).
Most lights (headlight, high beam, parking) are wired directly through switches. The brake and rear running light is wired through the Bulb Monitoring Unit (BMU) located in the relay box under the tank.  Signals are managed by the Flasher module, also located under the tank.

Other circuits such as neutral detect, speedometer, tachometer, clock and gear indicator are located in the instrument cluster.
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 18, 2018, 09:39:48 PM
So I went for a ride and was really impressed with the bike behavior with 2 exceptions :
 - instruments in the faring were dancing furiously all the time,
 - guttural vibration was slightly felt with speed 60 - 80 km/h but became really intrusive to the point of a strong feel even in the handlebar around 100 - 120 km/h
Bike was dropped in the past, tank was painted and faring has a slight crack in the left side touching tank.
My question is - could this kind of vibration be caused by lets say any imbalance in throttles, dirty injectors or faulty ignition set up, or something got really screwed during motorcycle drop. I suspected one of the crank bearings going out, but oil pressure lamp showed on turned of engine and never came back during a ride.
Title: Re: Starting the research on R80 and K75
Post by: rbm on July 18, 2018, 10:08:23 PM
IMO,  K75's should not vibrate the way you describe.  Something's up with that.  How pronounced were the vibrations?  Were the vibrations in sympathy with the engine speed or the road speed?

The dancing instruments is peculiar as well.
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 18, 2018, 10:17:50 PM
Definitely with engine speed, after you pull the clutch everything went away. I didn't look at tacho, but I believe 100 km/h was around 4000 rpm ?
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 18, 2018, 10:54:49 PM
No, it's not true - I just realized I only pulled the clutch changing gears and didn't do it going on 404 at 100 km/h.
So it could be a bearing in the tranny.
Title: Re: Starting the research on R80 and K75
Post by: Laitch on July 18, 2018, 11:03:04 PM
I suspected one of the crank bearings going out, but oil pressure lamp showed on turned of engine and never came back during a ride.
No, it's not true - I just realized I only pulled the clutch changing gears and didn't do it going on 404 at 100 km/h.
So it could be a bearing in the tranny.
Golly! The sky is falling! The bearings are ok. I can see their aura from here—a soothing mint green.

Because it's a neglected K75S, it needs its fairing fittings tightened (https://forums.bmwmoa.org/showthread.php?3152-K75S-Headlight-amp-Front-Fairing&s=30016a3f56af70511e196df13a1539fc&p=28005&viewfull=1#post28005), a dose of stuff the monkey (http://www.motobrick.com/index.php?topic=9185.0) and probably a tune up. Bad bearings would be a bonus.
Title: Re: Starting the research on R80 and K75
Post by: Laitch on July 18, 2018, 11:24:24 PM
Here's another thread (http://www.motobrick.com/index.php/topic,5607.msg35456.html#msg35456) that might interest you, Adam.
Title: Re: Starting the research on R80 and K75
Post by: blackie1 on July 19, 2018, 12:50:32 AM
the instrument cluster shake appears to be across the entire family to some degree.
you will be used to it before you know it.

http://www.motobrick.com/index.php/topic,9185.msg73158.html#msg73158

plenty of threads discuss this
Title: Re: Starting the research on R80 and K75
Post by: Martin on July 19, 2018, 01:35:25 AM
Once you synchronize your head shake with the instrument shake you won't even notice it.  :hehehe
Regards Martin.
Title: Re: Starting the research on R80 and K75
Post by: johnny on July 19, 2018, 04:24:19 AM
greetings...

trans needs a valve job... do you have shems...

j o
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 19, 2018, 05:38:39 PM
Seller called me today telling me his throttle bodys were way off and he corrected them.
Vibration subsided, he was able to take a bike to 160  km/h, but was still there.
I suggested my suspicion about gearbox / final drive bearing being on the way out and he confirmed the possibility
with his buddy ( head of BMW service in one of Toronto dealerships ).
He decided to take final drive, shaft and gearbox off to find out if this could be a culprit.
Will give me a message during this coming weekend.
Title: Re: Starting the research on R80 and K75
Post by: Laitch on July 19, 2018, 06:15:40 PM
Seller called me today telling me his throttle bodys were way off and he corrected them.
Vibration subsided, he was able to take a bike to 160  km/h, but was still there
He decided to take final drive, shaft and gearbox off to find out if this could be a culprit.
Will give me a message during this coming weekend.
This seller seems unusually accommodating. I hope this works out for both of you.
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 19, 2018, 06:25:58 PM
He wants to sell, he knows I ( and my wife ) want to buy.
Title: Re: Starting the research on R80 and K75
Post by: rbm on July 19, 2018, 06:49:27 PM
Golden opportunity.  While he has the final drive off, have him take clear pictures of the condition if the splines, both on the FD as well as the drive shaft.  These will be important ti understand if you have to potentially replace the drive shaft.  It will affect the sale price.
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 19, 2018, 07:03:44 PM
This is what he will do.
Today he took off a final drive and shaft, tomorrow a gearbox and clutch.
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 19, 2018, 09:38:36 PM
(https://s26.postimg.cc/6hddqbgzd/bmw_splines_1.jpg)
(https://s26.postimg.cc/wpoifp8sp/bmw_splines_2.jpg)

These are the pictures I got from him.
What do you guys think ?
Lots of grease :).
Title: Re: Starting the research on R80 and K75
Post by: rbm on July 19, 2018, 09:49:01 PM
Nice picture of the guy's bucket and toolset; not so good one of the splines.  They look kind of worn peering through the misty blur that is that picture.  It's hard to tell from all the grease covering the FD splines whether they are good or bad.  Maybe others have sharper eyes than I.
Title: Re: Starting the research on R80 and K75
Post by: The Mighty Gryphon on July 19, 2018, 09:52:52 PM
Personally, I think the pictures leave a lot to be desired.  I can't make any determination of the condition of the splines.  At least they look like they were very well lubed.

If it was me, I'd make a special trip to see them in person.  Good splines have nice wide flat spots at the top.  As they wear that flat area gets narrower until it's almost a knife edge, and then they strip out.
Title: Re: Starting the research on R80 and K75
Post by: Laitch on July 19, 2018, 10:49:46 PM
Ask him to get down on the level of that spline shaft of the final drive and take a couple of photos of it straight on with good lighting.
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 19, 2018, 11:11:21 PM
To me FD splines look much better than shaft splines.
What is the cost of a good shaft ?
And yes, I will ask him to clean the grease and make better pictures.
To go and see - I already made 2 x 140 km round trips, perhaps during the weekend.
Title: Re: Starting the research on R80 and K75
Post by: blackie1 on July 20, 2018, 02:51:33 AM
https://www.motobins.co.uk/

motobins can supply a spline replacement for the rear of your driveshaft for 66 UK pounds plus freight,so long as your final drive splines are still in good nick. I am certain there are posts on here that you can do some research.


i bought this spline replacement and managed to source a second hand final drive unit from the USA that was still in tip top condition.
new driveshaft splines attached to worn final drive will chew out your new splines, so best to try and get good teeth on both mating surfaces.
both parts are presently shelved in my garage, ready for when I decide to have a local engineering outfit weld the new splines on.
having the replacements on my shelf gives me a sense of smug self satisfaction.

i am smugger than smuggler that has 2 x smug rats in either pocket  :neener:

Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 22, 2018, 11:03:07 AM
Next pictures delivered :

(https://s26.postimg.cc/o4iblw7qh/bmw_pics_1.jpg)
(https://s26.postimg.cc/bd45fe5o9/bmw_pics_2.jpg)
(https://s26.postimg.cc/5c6gih3o9/bmw_pics_3.jpg)
(https://s26.postimg.cc/3kdhnks15/bmw_pics_4.jpg)
(https://s26.postimg.cc/o4ibm2fi1/bmw_pics_5.jpg)
Title: Re: Starting the research on R80 and K75
Post by: rbm on July 22, 2018, 12:08:13 PM
The clutch splines, transmission input splines and drive shaft input splines look in good order.  They are dry and need lubrication badly. Hopefully the owner does that while he's so far into the teardown.  You still don't know the true condition of the drive shaft output splines and final drive input splines.
Title: Re: Starting the research on R80 and K75
Post by: bocutter Ed on July 22, 2018, 12:20:59 PM
They are dry and need lubrication badly.
Prior photos had them covered in grease. These would be "cleaned for inspection photos".
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 22, 2018, 12:38:21 PM
Everything will be greased, I sent another request concerning 2 first pictures with clean splines for FD and corresponding end of the shaft, however in the daylight this end of the shaft looks good to me. The most suspect for me are FD splines.
Title: Re: Starting the research on R80 and K75
Post by: The Mighty Gryphon on July 22, 2018, 12:44:42 PM
Prior photos had them covered in grease. These would be "cleaned for inspection photos".

+1  Cleaning them showed how good the splines are. 

Waiting for final drive and driveshaft output spline photos.  IMO those are the important ones.  Judging from the photos posted, they should look pretty good.
Title: Re: Starting the research on R80 and K75
Post by: Adam M on July 27, 2018, 04:18:14 PM
To finish this thread I should add some pictures :

(https://s26.postimg.cc/azsle276h/P8270001.jpg)

(https://s26.postimg.cc/tfd2bgt0p/P8270002.jpg)

We picked up a bike from the seller this morning and made 70 km on rural and less rural roads, crossing Toronto in dense traffic around noon, me on the bike and my wife in our car. Bake behaves exceptionally well, is very comfortable ( other than too sporty riding position for me, but it's not as bad as I expected ), brakes are powerful an well modulated, feels very solid in turns and slow speed maneuvers, gears and clutch work quietly and smoothly.
After some time spend at home we decided to try it two up in afternoon city traffic and however I got sweaty ( it's hot day anyway ) it was done with ease.
We are very happy to have this bike in our possession and looking forward to have lots of fun on it.

(https://s26.postimg.cc/4tr57r88p/image3.jpg)
Title: Re: Starting the research on R80 and K75
Post by: natalena on September 01, 2018, 07:15:20 PM
Congrats on getting the K re-commissioned and back on the road. Likewise, I've had many MC's, but the K75S just has something that makes it enjoyable to ride.
Title: Re: Starting the research on R80 and K75
Post by: Adam M on September 02, 2018, 10:28:48 AM
Thank you.