BMW K bikes (Bricks)

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1Back to top Go down   K75 somethin' Empty K75 somethin' on Tue Sep 24, 2019 5:45 pm

Woodie

Woodie
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This came home on the weekend, 23,289 kms and built in March of 1990:

K75 somethin' K75rt10
As usual lots of cleaning and general loving to - hopefully - get it to something resembling this:
K75 somethin' 13318712
This one might be on-going for a while as my Missus was extremely patient during the first K reno but will be expecting more work done on the house while this project unfolds.   Laughing


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1985 K100RT
52667
"Keep your stick on the ice.  We're all in this together."  Red Green
    

2Back to top Go down   K75 somethin' Empty Re: K75 somethin' on Wed Sep 25, 2019 3:23 am

Arlina

Arlina
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K75 somethin' Eu-log10  K1100RS/LT - R1200RT - R1100RS (RIP) - Cagiva SST 350 Ala Verde
    

3Back to top Go down   K75 somethin' Empty Re: K75 somethin' on Wed Sep 25, 2019 6:31 am

Woodie

Woodie
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Thanks Arlina, I'm definitely planning on modifying the exhaust.  I can get this silencer locally:K75 somethin' _59_111
I know nothing of the science of exhaust systems, and its obvious that Akropovic makes a lot of money because it is a science, but I'm hoping this can be made to work.  It is off of a 450 KTM.  I can live with the sound changing somewhat but the last thing I want are loud pipes.  Also, would this can develop enough back pressure to prevent any harm to the engine?


__________________________________________________
1985 K100RT
52667
"Keep your stick on the ice.  We're all in this together."  Red Green
    

4Back to top Go down   K75 somethin' Empty Re: K75 somethin' on Wed Sep 25, 2019 6:55 am

Arlina

Arlina
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This muffler comes from a 1-cilinder bike, dunno what sound it will give.
I know the original exhaust is the best, for sound and performance, with a bit of help from an axl grinder and some welding it should be possible to place it high on the bike without being too big.
Haven't got examples of that configuration, just slipped my mind Smile


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K75 somethin' Eu-log10  K1100RS/LT - R1200RT - R1100RS (RIP) - Cagiva SST 350 Ala Verde
    

5Back to top Go down   K75 somethin' Empty Re: K75 somethin' on Wed Sep 25, 2019 8:10 am

charlie99

charlie99
VIP
VIP
looks a good project ..to happen


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OK75 somethin' Au-log10

"redframe" rs "bitsa"  with many contributions from the k100 community ,,with many thanks
    

6Back to top Go down   K75 somethin' Empty Re: K75 somethin' on Wed Sep 25, 2019 2:39 pm

chris846

chris846
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I think so long as you keep the original headers & collector, you can't go too far wrong. If possible, the link pipe from the collector to the can should be close to the original diameter too.
I hear lots of mention of 'back pressure', but afaik the header length & diameter are the only things that have the potential to mess up an engine, and this obviously isn't an issue with keeping the stock header. The silencer just, well, silences - as much or as little as you want. IMHO you can't usually beat a stock pipe for performance/noise reduction. A meaty sound and a hole in the midrange before the (same amount of) power arrives (much more sharply as a consequence) does work wonders on the brain though (and I'm talking about mine too).
A Graham Bell's book 'four stroke performance tuning' is a straightforward read, and a bit of a bible.



Last edited by chris846 on Wed Sep 25, 2019 2:40 pm; edited 1 time in total (Reason for editing : spelling like a gibbon)


__________________________________________________
The Longest Lunch
    

7Back to top Go down   K75 somethin' Empty Re: K75 somethin' on Thu Sep 26, 2019 6:56 am

Woodie

Woodie
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I'll have a look for the book, should be an interesting venture into something I know squat about. This will likely take some experimentation on my part to find an acceptable noise level while reducing the size and location of the silencer.  Lucky for me I 'know a guy' who has a shop that does custom stainless, and now titanium, performance exhaust systems. I'll be getting him to bend the pipe from the collector to the silencer.  

First things first though - I have a gas tank to clean out.  Very Happy  It could be worse but I still have my work cut out for me.  Current plan (hah!!) is to get the bike running and then go about systematically (very loosely speaking of course) modifying it.


__________________________________________________
1985 K100RT
52667
"Keep your stick on the ice.  We're all in this together."  Red Green
    

8Back to top Go down   K75 somethin' Empty Re: K75 somethin' on Thu Sep 26, 2019 3:02 pm

chris846

chris846
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Life time member
It's possible to devise a link pipe in your shed: stainless tube bends - 15', 30', 45', 60' can be bought for £notverymuch on oohbay, along with tubing chosen to slide inside it. Slit the ends of the bends and use jubilee clips to clamp them to the tube. You can play for hours, getting things to line up exactly as you want, and then just take the 'finished' article to your welder pal.
Much more time consuming!


__________________________________________________
The Longest Lunch
    

9Back to top Go down   K75 somethin' Empty Re: K75 somethin' on Mon Nov 04, 2019 8:14 pm

Woodie

Woodie
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Life time member
I believe I might be in the midst of what Douglas Adams refers to as "the long, dark teatime of the soul" - at least my own version of it -  a project bike in the shop (shed) and too many pressing responsibilities to be able to spend time with and on said project bike.

I've been alternately buying parts and cleaning the gas tank.  I think cleaning a tank is another one of the great K rites of passage, similar to changing the ceramic seal on the oil/water pump.   Very Happy

A few questions:  can rad hoses be reshaped?  
K75 somethin' Rad_ho10
The "cheap bastid" part of me would like to use an original RT hose but reshape it and send it through the hole in the cover.

Next question:  this K75 came with ABS1, including a brain replaced under warranty.  One of my goals with this build is to get it as light as is reasonable so I will be removing the ABS.  Removing it should be fairly straight forward but I would like to re-install it on my '85 K100 as it would be quite beneficial on the big fatty I think.  Swapping the front end and rear wheel, etc. should be fairly straight forward but the wiring loom is a bit more of a challenge.  Why BMW chose not to just add an auxiliary ABS loom is beyond me but would it be feasible to remove this section from the K75 loom and add it to the K100 loom?  I know that I have to swap the bread box as well.


__________________________________________________
1985 K100RT
52667
"Keep your stick on the ice.  We're all in this together."  Red Green
    

10Back to top Go down   K75 somethin' Empty Re: K75 somethin' on Mon Nov 04, 2019 10:00 pm

RicK G

RicK G
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With regard to the front end I found that the Honda Transalp has 41mm forks and the length is good with twin discs so it makes for a good front end.
I tried the upside down forks from Suzuki and Kawasaki but lock to lock is very limited where the Honda gives the original lock because you use the standard triple tree.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1993 K1100 LT, 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 for now
    

11Back to top Go down   K75 somethin' Empty Re: K75 somethin' on Tue Nov 05, 2019 11:53 am

chris846

chris846
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In my own limited world, there is no known solution to 'coughing up and paying for the hose-with-a-kink that is specific to the slim jim rad on the K75s'.
Many have tried (actually just me) and just as many (always me) have failed.
The offset between rad and crank cover is just too ding dong close*

As for grafting an ABS loom onto your K100, I've never done this.
However, I have done the opposite  Very Happy
Ergo it is possible. It is also a several cups of coffee, decent radio station, what else would I be doing with my life, kind of a job.

*you could always fit a standard width rad off any K100 or a K75anythingelse.


__________________________________________________
The Longest Lunch
    

12Back to top Go down   K75 somethin' Empty Re: K75 somethin' on Tue Nov 05, 2019 1:14 pm

Point-Seven-five

Point-Seven-five
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__________________________________________________
Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

13Back to top Go down   K75 somethin' Empty Re: K75 somethin' on Tue Nov 05, 2019 3:34 pm

Laitch

Laitch
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@Woodie wrote:. . .  can rad hoses be reshaped?  

The "cheap bastid" part of me would like to use an original RT hose but reshape it and send it through the hole in the cover.
Let that bastid run free! There's this to try.


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1995 K75 73,000 miles
K75 somethin' Usa-lo10
    

14Back to top Go down   K75 somethin' Empty Re: K75 somethin' on Tue Nov 05, 2019 8:17 pm

K75cster

K75cster
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I'm with Arlina on that Exhaust, would be a treat to see. Dual radiators? $1500 for new K1200 twin radiators and $110 for Wr450 radiators, off of Oopsbay. Some smaller pipes to muddle over on the WR rads. rear wheel travel on the St's were also aided by having the R series sloping backward allowing greater travel. Not so sure about that for the K though. Watching with interest anyway. Smile
Oh yes do the chores first and then play with the beastie


__________________________________________________
Keith - 1987 K75c with r100rt replica fairing and half of a 1984 K100rt 1992 K1100LT a blue one

The Clever are adept at extricating themselves from situations that the wise would have avoided from the outset - QUOTE from david Hillel in Out of the Earth.
    

15Back to top Go down   K75 somethin' Empty Re: K75 somethin' on Tue Nov 05, 2019 10:04 pm

Woodie

Woodie
Life time member
Life time member
It was interesting to me to dig into the K75RT and begin to get a grasp of the similarities and differences between it and the K100.  The K75RT rad has a clip that holds it away from the engine and it is this that keeps the rad hose out of the crank cover.  I think in this sense the 75 is a 100 with the front cylinder lopped off.  The clip on the rad makes it possible to have the 100 fairings work on the 75.  

I do like the GS exhaust but my chances of picking one up for small change here in Canada are meager.  Same for the front end off of a Transalp.  I don't think I have ever seen one of those here in the wild and a quick perusal of the Canadian buy and sell offered up nothing.  I'll keep on the lookout though.

One of the great things about picking up this particular K75 was that it needed some serious loving.  I wouldn't have been able to contemplate the changes I want to do if it was a mostly stock bike and in running condition.  And getting to meet Lorne (the PO) was a huge plus too.

Winter is coming (just like GOT) and I'll soon have more time to spend out in the shop where there is a wood stove, CBC radio - our national radio service - and coffee.  Very Happy  Next steps will be to complete the tank cleaning, replace a sh!t ton of rubber bits and get the bike running again.  As soon as I get it running I will get it not running by tearing it back down to nothing.  Thank you all!


__________________________________________________
1985 K100RT
52667
"Keep your stick on the ice.  We're all in this together."  Red Green
    

16Back to top Go down   K75 somethin' Empty Re: K75 somethin' on Wed Nov 06, 2019 3:30 am

chris846

chris846
Life time member
Life time member
"I think in this sense the 75 is a 100 with the front cylinder lopped off. "


K75 somethin' 03910

Yep.


__________________________________________________
The Longest Lunch
    

17Back to top Go down   K75 somethin' Empty Re: K75 somethin' on Wed Nov 06, 2019 6:57 am

Woodie

Woodie
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Life time member
K75 somethin' 44271


__________________________________________________
1985 K100RT
52667
"Keep your stick on the ice.  We're all in this together."  Red Green
    

18Back to top Go down   K75 somethin' Empty Re: K75 somethin' on Wed Nov 06, 2019 7:45 am

Dai

Dai
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Life time member
(shakes head slowly)  Rolling Eyes


__________________________________________________
'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

19Back to top Go down   K75 somethin' Empty Re: K75 somethin' on Wed Nov 06, 2019 7:52 pm

K75cster

K75cster
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Life time member
Oh Chris you surgeon you  Cool


__________________________________________________
Keith - 1987 K75c with r100rt replica fairing and half of a 1984 K100rt 1992 K1100LT a blue one

The Clever are adept at extricating themselves from situations that the wise would have avoided from the outset - QUOTE from david Hillel in Out of the Earth.
    

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