BMW K bikes (Bricks)

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1Back to top Go down   Forks and oil Empty Forks and oil Mon Aug 23, 2010 11:14 pm

Ned

Ned
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Hello Brick Pilots,

I have a K100RS 2V (1986), see my Avatar space for details. I am about to service the forks, callipers and change the front tyre. The forks probably require 330ml of oil and here is my question:
how can i tell which forks I have?

Can anyonetell me how to positively identify them please.

Forks and oil ForkOilTable


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I reserve the right to voice my opinions on any subject known to man
Ned

05/1986 (K55) K100RS Motorsport (Europe), Production Code: 0503, 110k km, VIN:0140519 (SOLD)
1976 Honda Goldwing GL1000 (naked)
1997 BMW K1200RS red, VIN: WB10544A1VZA22667
    

2Back to top Go down   Forks and oil Empty Re: Forks and oil Tue Aug 24, 2010 4:25 am

Guest

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I'd say you've got the 360ml fill forks on your model, same as mine, until I swapped them for the sport forks from a K75S with the tiny 'S' inscribed in the aluminium top cap. Unless a previous owner did something you don't know about that's your fill amount. If you do put only 330cc of oil in, and your forks require the 360cc level, you'll notice the damping feels spongy and vague. Too much oil and she'll jar your fillings over tiny road irregularities.

    

3Back to top Go down   Forks and oil Empty Re: Forks and oil Tue Aug 24, 2010 5:12 am

blaKey

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If your fork legs have a "rib" running down them (on the front edge), they are Fichtel and Sachs. 360 +/- 10cc.

The Showa have no "rib" and are for K75's 1983 onwards. 410cc at oil change or 420cc when dry (from a rebuild for example).

According to the Haynes manual.


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Neil
K100RS 1986 RED!

Dress for the ride and the potential slide.
    

4Back to top Go down   Forks and oil Empty Re: Forks and oil Tue Aug 24, 2010 7:14 am

Ned

Ned
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Thank you! It looks like 360cc is it.


__________________________________________________
I reserve the right to voice my opinions on any subject known to man
Ned

05/1986 (K55) K100RS Motorsport (Europe), Production Code: 0503, 110k km, VIN:0140519 (SOLD)
1976 Honda Goldwing GL1000 (naked)
1997 BMW K1200RS red, VIN: WB10544A1VZA22667
    

5Back to top Go down   Forks and oil Empty Fork oil? Wed Feb 09, 2011 7:33 pm

redbeemer

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I have a 1992 16 valve K100rs and my original BMW handbook states 400cc of oil in each leg at oil change!

    

6Back to top Go down   Forks and oil Empty Re: Forks and oil Wed Feb 09, 2011 7:52 pm

japuentes

japuentes
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Hi there, as far as I know if your forks have and S stamped in the top nut (the one you have to retain to release the filling plugs) then your suspension is sport type and requires 280 cc.
Best regards
JAP

    

7Back to top Go down   Forks and oil Empty Re: Forks and oil Thu Feb 10, 2011 12:57 pm

wikur

wikur
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My -88RS with an F&S fork has been happy with 370 ml in each leg.
No S stamped.
Don`t overtight the drain plugs when changing oil.
I had to fit helicoil inserts due to hamfisted spannering.
Cheers,Wikur!

    

8Back to top Go down   Forks and oil Empty Re: Forks and oil Thu Feb 17, 2011 11:36 am

Adiwan Djohanli

Adiwan Djohanli
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Silver member
Can anyone advice me please?

My left fork is leaking oil, means I need to replace the seal / gasket. On the lower fork bridge it says "Paolo Tardossi" (?).

How much oil shall I put in each fork?

Thanks.


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Adiwan Djohanli
Jakarta-Indonesia[i]
    

9Back to top Go down   Forks and oil Empty Re: Forks and oil Tue Feb 22, 2011 3:34 am

wikur

wikur
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Silver member
I think you`ve got this.
Forks and oil 00310

Its an aftermarket forkbrace for K`s earlier than -88.
Made by "Paolo Tarozzi,Italy".
0,37L in each leg should be fine,works for me.
Cheers,Wikur!

    

10Back to top Go down   Forks and oil Empty Re: Forks and oil Tue Feb 22, 2011 4:34 am

Adiwan Djohanli

Adiwan Djohanli
Silver member
Silver member
Hello Wikur,

Thank you for the information.

I am travelling out of town now. I will upload the picture of the fork on my bike.

Cheers.


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Adiwan Djohanli
Jakarta-Indonesia[i]
    

11Back to top Go down   Forks and oil Empty Re: Forks and oil Sat Dec 17, 2011 2:11 am

club_c

club_c
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I hate to crack this thread open again, but I guess this place is as good as any to ask.

1985 K100RS. Has 'Brembo' forks with rib on the front, no 'S' on the cap. How much oil per leg? I'd like to do this in the next couple of days.


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"There's never enough time to do it right, but there's always time to do it over."

1988 K100RS SE VIN 01477554
    

12Back to top Go down   Forks and oil Empty Re: Forks and oil Sat Dec 17, 2011 3:58 am

blaKey

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If your fork legs have a "rib" running down them (on the front edge), they are Fichtel and Sachs. 360 +/- 10cc.


__________________________________________________
Neil
K100RS 1986 RED!

Dress for the ride and the potential slide.
    

13Back to top Go down   Forks and oil Empty Re: Forks and oil Sat Dec 17, 2011 12:28 pm

club_c

club_c
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Ok. The leg has "BREMBO" stamped near the top which was throwing me off.


__________________________________________________
"There's never enough time to do it right, but there's always time to do it over."

1988 K100RS SE VIN 01477554
    

14Back to top Go down   Forks and oil Empty Re: Forks and oil Sat Dec 17, 2011 4:23 pm

K-BIKE

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I saved the following which was written by the very knowledgeable Brian Curry so this is all his work.


Front Fluid Quantity and Suspension Response



November 1998

Brian Curry

My latest K75RT, a 92, had Showa
forks. This is the first I had Showa's. The front of the bike was scary under
braking. It dove like crazy. I thought I needed new Progressive Springs.



As part of the prep for running
it to the West, I drained and refilled the forks. For some reason, I checked
the amount of fluid that came out of the first fork, ~360 cc's. Odd number it
seemed. The Non-Showa RT's took 280 cc, and the non-sport suspension was
supposed to take 330 cc and the drained amount was more than this.



I checked the owners manual. It
said 280 and 330 cc's. Hmmm. I checked the manual version date. It was old...
and pre Showa... Time to call the dealer.



Lee Kundrat, of Otto's BMW
Cycles, told me Showa forks were supposed to take 410 cc's.



OK, I tried that and put 410 cc's
of BMW 7.5W oil in each leg.



Then I rode the bike. Even I, the
suspension idiot, could tell the difference. SmileSmile It was a night and day
difference. The dive was much reduced!! The front end suspension felt much more
composed.



Then I thought about it a bit.
The new, proper, larger fluid volume reduces the air volume above it, compared
to the way I got the bike. This means that when the fork compresses, the air
PRESSURE increases much faster than when the volume is larger. Increasing air
pressure acts like a rising rate spring. Effectively, putting more fluid in the
fork increased the spring rate a lot when the fork tried to dive. (Some time
back, HD had a brake dive reduction scheme, by isolating an air chamber that
connected to above the fork oil. It gave a "higher" spring rate, when
you were on the brakes and the fork air volume was cut off from the chamber.)



Having the proper amount of fluid
in the forks IMO, eliminated the need for a spring transplant and made the CC
jaunt much more pleasurable.



So, if you want more
"cushiness" and "plushness" although with more dive, put in
less fluid. If you want more "control" and "firmness" and
"less dive" put in more fluid. Remember there is a limit on how low
or high you can go. If you go too low, you can hear the transition from air to
fluid as the fork valving compresses. Shock "absorption" will vary a
lot depending if there is air or oil going through the restriction orifices. If
you go too high, the fork tube pressure will go REAL HIGH. The suspension may
appear to be "solid" or "locked". You might be able to blow
the fork seals or O-rings out. Either are not be good things. Remember, when
you deviate from the BMW factory values, you are on your own. Travel with care.


BWM specified fork oil
quantities/capacities have varied over the years. Here is a table of values:


Fork Oil
Quantities/Capacities



Model Leg Change Disassembl


K75 Showa L
410 cc 420 cc



K75 Showa R
410 cc 420 cc






K75 BMW L 330 cc


K75 BMW R 330 cc





K75 Sport L
280 cc



K75 Sport R
280 cc



(Has an "S"
stamped on the aluminium plug on top of the leg.)






*16V*


K1100LT L 350 cc 400 cc


K1100LT R 400 cc 400 cc





K1100RS L 350 cc 400 cc


K1100RS R 400 cc 400 cc





K1, K100RS L
380 cc 400 cc



K1, K100RS R
380 cc 400 cc


There is
a Service Instruction 31 026 92 (2547) which is supposed to have additional
information.



A ">" indicates that
the data is correct for models up to that model year from either start of
production, or an earlier date when the value was different.



This data is was correct as of
Oct 4, 1993. After that, you are on your own. But it may be some help. Why does
the amount vary from the Left to Right leg? Don't know. BMW says it does.

    

15Back to top Go down   Forks and oil Empty Re: Forks and oil Mon Dec 19, 2011 7:49 pm

club_c

club_c
Life time member
Life time member
Yep, 360 came out, 360 went back in. Thanks fellas.


__________________________________________________
"There's never enough time to do it right, but there's always time to do it over."

1988 K100RS SE VIN 01477554
    

16Back to top Go down   Forks and oil Empty Forks and oil Sat Dec 31, 2011 1:00 pm

Lazyboy

Lazyboy
Silver member
Silver member
Shocked I have my K100RT original Riders Handbook and it recomends 330ml per fork. I found SAE 5 or 10 Fork Oil too soft and have been using SAE15 with good results for many years.

    

17Back to top Go down   Forks and oil Empty Re: Forks and oil Sat Dec 31, 2011 2:01 pm

Inge K.

Inge K.
VIP
VIP
According to my oldest Haynes manual (`88) 330 ml was used on the model without a fairing.
All models with a fairing should have 360 ml.
My oldest genuine manual (04/88) also confirm these volumes.

And to make the confusion complete.....my riders handbook (3rd quarter `85) recommends
360 ml on all models



...........but it also was a revision on the forks during `85.


Inge K.



    

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