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post #1 of 6 (permalink) Old Aug 23rd, 2006, 6:45 am Thread Starter
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K100 Fork oil

I searched for a thread on this topic and did not see one. Sorry if it had already been asked before.

Concerning K100 machines. Changing the fork oil. Do I make the extra trip to find the oil specified in the SM (BelRay, Castrol, Golden Spectro, Mobil, Shell) or are traditional Fork oils 5wt, 10wt and 15wt the same thing?

I mean to say, are BMW machines that picky when it comes to special fluid?

What do you other early K bike owners use? I prefer a stiffer ride on the front, so I was considering putting in 15wt oil until I saw the fluid specs.

Thanks!

Drew Mobley
GT Bean Counter
Atlanta, Ga

Yamaha '86 SRX600, '87SRX250
'88 Honda NX650
'66 Sears Saber 50
'85 BMW K100RS
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post #2 of 6 (permalink) Old Aug 23rd, 2006, 8:30 am
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Plain old fork oil works just fine.
BTW I used #15wt. Spectro in my K100. It helped stop the pogo effect on the front end.
Bruce C

Bruce C
'04 K1200RS Capri Blue(totaled)
2008 Triumph Sprint ST
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post #3 of 6 (permalink) Old Aug 23rd, 2006, 8:41 am Thread Starter
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That is a big help. Thanks

Drew Mobley
GT Bean Counter
Atlanta, Ga

Yamaha '86 SRX600, '87SRX250
'88 Honda NX650
'66 Sears Saber 50
'85 BMW K100RS
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post #4 of 6 (permalink) Old Mar 12th, 2010, 10:34 pm
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How do I fill my forks?

Hello all,

Sorry for the stupid question, but this is my first post to K-Bikes, so if I can't ask a stupid question now, when can I?

I have an 86 K100RS with 62,000 miles on the clock, and I am waiting for my Haynes and Clymer manuals to show up from back home in the States. In the mean time, I have changed all of the oil except the fork oil. I can figure out how to drain the stuff, but how the heck do I fill it? I pried off the little red plastic caps which have an O-ring, but I cannot pour oil in. I tried turning the flat-head scew that is about 1" deep inside, but it stops after about 7 clicks counter-clockwise.

As for the oil: I bought 10wt Castrol, but now that I have found this thread I am thinking that I should have gone with 15wt. I'm from Colorado, where the weather is nice and cool, but for now I live in Australia, where is always stinking hot. Should I use a 15wt oil?

Any help you guys can provide would be greatly appreciated.

Regards,

Josh

CU '93
Indecision may or may not be my problem.

4/1984 HJ47 'Patches' OME, H55, p/s, a/c.

7/1984 FJ40 LX 'Lexie' OME, H55, p/s, a/c, Lockers.

6/1986 BMW K100RS 'The Brick'
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post #5 of 6 (permalink) Old Mar 13th, 2010, 11:42 am
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Quote:
Originally Posted by Patches
Hello all,

Sorry for the stupid question, but this is my first post to K-Bikes, so if I can't ask a stupid question now, when can I?

I have an 86 K100RS with 62,000 miles on the clock, and I am waiting for my Haynes and Clymer manuals to show up from back home in the States. In the mean time, I have changed all of the oil except the fork oil. I can figure out how to drain the stuff, but how the heck do I fill it? I pried off the little red plastic caps which have an O-ring, but I cannot pour oil in. I tried turning the flat-head scew that is about 1" deep inside, but it stops after about 7 clicks counter-clockwise.

As for the oil: I bought 10wt Castrol, but now that I have found this thread I am thinking that I should have gone with 15wt. I'm from Colorado, where the weather is nice and cool, but for now I live in Australia, where is always stinking hot. Should I use a 15wt oil?

Any help you guys can provide would be greatly appreciated.

Regards,

Josh
Little red plastic caps????? Flat head screws???? Could there be some kind of aftermarket preload adjuster in there?

As far as I remember all them bikes had an Allen Hex head bolt in the cap to refill the forks.

You may have to take off the complete cap assembly to figure that one out, and see if there is a preload adjuster. But careful as you unscrew the caps,there may be extra shims in there to preload the springs ,so there may be enough tension to push the caps out hard. Very fine threads, you do not want to damage those.....

Doing that you will also see if you have the progressive springs in there....a must on those bikes!

But I have seen a few riders in the old days putting too much preload and too heavy oils in their front ends to correct stability/handling problems.....not a good thing !

I have to edit here....a good think is to dismantle the forks every few years for cleaning/inspection. I remember having to replace a couple pistons in there, but look here, it should give you a good idea of what you are looking at:

http://www.maxbmwmotorcycles.com/fiche/fiche.aspx

P.S. My old 85 K100RS sure loved Colorado....

Benelli 50cc at 14
Yamaha RD 200 at 16
Yamaha RD 350 at 17
Honda CB 750 F at 18
Honda V45 Sabre at 24
BMW K100RS at 27
BMW R100GS at 34
BMW K1200RS at 53

Last edited by H96669; Mar 13th, 2010 at 12:00 pm.
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post #6 of 6 (permalink) Old Mar 20th, 2010, 8:22 pm
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Thanks 96669,

My owners manual which came with the Brick shows those little allen screws, so I wonder if I do have an after-market fork...? I do not have any of the pogo stick problems with this bike, and it handles wonderfully, so I am certain that I at least have progressive springs in there. The previous owner put a Staintune exhaust on there, so he may have added the springs. Unfortunately for him, he developed Parkinsons, and I can no longer ask him.

Thanks for that link: I will pull mine apart and see what they look like. I was hoping there was an easier way to go about, that's all.

My old 1150GS loved it back home too; so did I. The longer I live in the land of Big Brother (Australia) the more I miss home. I hope we will be moving back to the States in the next year or so, but jobs, etc. will determine that. We will likely be bringing the Brick back with us in the shipping container, so I don't mind putting a bit of work into it.

Josh

CU '93
Indecision may or may not be my problem.

4/1984 HJ47 'Patches' OME, H55, p/s, a/c.

7/1984 FJ40 LX 'Lexie' OME, H55, p/s, a/c, Lockers.

6/1986 BMW K100RS 'The Brick'
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