BMW K bikes (Bricks)

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duck

duck
Life time member
Life time member
I decided that I should put some Showa forks on my K75 turbo instead of the S forks I had on hand when I renovated it.  I already have a nice set of fork trees from a 93 that fit the Showa fork diameter so all I needed was a pair of forks.

I offered a Fleabay seller $140 shipped for a nice set of 94 Showa forks from a 48K K75 and the seller accepted my offer.  I think $140 shipped is a good deal for a nice set of forks. (Although I now wish I'd offered $100 - LOL.) I pulled one of the forks caps off to see what springs they have and they've got the stock progressive springs and spacers in them.

The seals aren't leaking, the fork tubes are perfect and, from their general appearance, they seem to have come from a well-cared for, always garaged bike.

Given their overall condition, I'm tempted to just drain them, refill them with some new Honda 10W, install therm and then see how they ride....


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Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

Tom GKR

Tom GKR
Life time member
Life time member
G'day Duck,put the very same question to a an excellent local mechanic who said don't change fork oil until seals need replacing.If oil is drained in the normal manner,a small amount of oil will be left in the forks unless you have a pump like Ulrich's.This pump completely removes oil from the forks.Just a thought. Cheers Tom

    

RicK G

RicK G
admin
admin
The lubricating qualities of the oil is what gives your forks a long life and leaving it there till the seals leak is a very unproductive way of maintenance.
Considering how easy it is to change I do mine yearly or at least every 20000km. If you are concerned about the remaining used oil contaminating the new oil then do a double change a week apart. Oil is cheap if you compare it to the cost of a new set of sliders or forks.


__________________________________________________
"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 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

duck

duck
Life time member
Life time member
That's a good idea.  Since I haven't installed them yet.  I can drain them,refill them a bit,invert them few times, drain, refill and install.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

tgolden

tgolden
Silver member
Silver member
Tom Grabau wrote:If oil is drained in the normal manner,a small amount of oil will be left in the forks unless you have a pump like Ulrich's.This pump completely removes oil from the forks.

What pump is this? I've never heard of a pump to change fork oil.

Regards


__________________________________________________
1985 K100RS USA Model WB1051300F0042533 - Original Owner
Delivery: 04/85 - Motorradhaus Ebert, Höchberg, Deutschland
    

Tom GKR

Tom GKR
Life time member
Life time member
G'day Rick and Tgolden, Your advice is spot on and makes sense.Maybe the mechanic was looking for more seal work.
The pump concerned is a sort of home made adapted refrigeration gas pump.Maybe PM Ulrich_Grabau for more details.Cheers Tom

    

Waz

Waz
Life time member
Life time member
How often should you take your forks apart and clean them up inside? Img_5321

Like this Tom?

    

Guest

avatar
Guest
How often should you take your forks apart and clean them up inside?

I believe that you should do this every 25 years whether it need it or not! My bike is only 23 years old so I leave it a bit longer. Wink

    

duck

duck
Life time member
Life time member
You'd be amazed at how much crap can build up inside of forks.  I had one pair of forks that had so much crap settled in the bottoms of them that they wouldn't even drain.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

AJ.Valente

AJ.Valente
Life time member
Life time member
Had the seals replaced when I bought the bike 2yr ago-cost $300. According to the manual, fork oil s/b changed yearly. I asked a few friends why I should change perfectly good oil, it's a sealed system, what could go wrong? 

Well, the oil eventually looses it's property to lubricate the seals, and then the seals go bad. So, it's either another $300 for seal replacement, or change the oil periodically. I've decided on every 2-years (with inspection 1) because every year seems excessive on a road bike. 

 Examined a number of different oils on the market. Essentially, I looked for those with certain additives, in particular, a seal lubricant.  The oil is cheaper larger quantities, so I get 2L at a time, enough to perform 2-replacements.

Now my question. The oil I'm currently using is clear, and the oil I just replaced is blue. So, what's the deal with fork oil color?  :|


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'98 K1200RS Marrakesh Red

My old K100 RT Pics and Mods
    

xpc316e

xpc316e
Gold member
Gold member
I have just had the forks apart on my K1100LT.  I do not know when they were last stripped, or indeed when the oil was changed.  The current work is in response to a weeping seal on one side.

The fork oil was really black, and when I pulled off the sliders there was quite a lot of congealed gunge in the bottoms.  This has now been cleaned out, and the forks are about to go back together.  I really think that whoever had the bike before me left it too long before changing the oil; it is not such a big job to drain and refill the forks oneself.  In addition, gaiters are also being installed in order to give the seals an easier time.


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VIN 0191428, 1991 K100LT, formerly owned by Lancashire Constabulary. This old warhorse is now 'out to grass' and living in retirement in Suffolk, where it will be showered with appropriate love and care.

VIN 6459609, 1992 K1100LT, another ex-Police machine, even though she now looks like she is a former fire engine.
    

duck

duck
Life time member
Life time member
I'm going to pump them and flip them over a few times over the next few days.  Hopefully, if there's any collected crud in the bottoms of therm then that will get it suspended in solution prior to draining.  Then I'll fill, redrain and refill as I don't want to dismantle them until I need to replace a seal.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

tgolden

tgolden
Silver member
Silver member
bikerboy wrote:How often should you take your forks apart and clean them up inside?

I believe that you should do this every 25 years whether it need it or not! My bike is only 23 years old so I leave it a bit longer. Wink


I do mine every thirty years whether they need it or not. I've scheduled April 2015 to have a go at it.


__________________________________________________
1985 K100RS USA Model WB1051300F0042533 - Original Owner
Delivery: 04/85 - Motorradhaus Ebert, Höchberg, Deutschland
    

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