K75RT Fork Oil Change

[Uffda]

Basic question and looking for reassurance.  Just finished doing my first valve check/adjust and moving on to fork oil replacement.  Everything is a first time for me since I have no previous mx experience to rely upon.  That's why I have enjoyed lurking on this site and gathering "experience" from everyone else.
Anyway, I picked up the fork oil today, read the Clymers chapter, popped off the plastic cover on my forks and it looks easy to remove the fill plug.  I can even get at it without removing the dashpad, fairing, or handlebars. Which makes me wonder if I am missing something here.  For a 95 K75RT, is that all there is to it?  Loosen and remove the filler plug with a 6mm hex key?  I'm aware of the drain plug warnings (don't over torque and strip it) but I don't want to start draining the fork oil until I know I can refill it.

[frankenduck]

Just be patient when refilling it.

[TimTyler]

Consider removing the front wheel and draining the forks by removing the big hex bolts that screw up from the bottom. There's no chance you'll strip those. Have replacement crush washers and a torque wrench ready to put them back in.

A meat injector makes adding the fork oil easy.

[Motorandy123]

There sometimes is a lot of sludge so it's better to totally remove the forks but you can just
open the tops and bottoms and let it drain for a long while (15 - 20 minutes) to make sure as
much as possible is drained. Then close the lower bolt. You can put a dab of RTV around the
bolt and make it fairly loose for a good seal without striping. Then refill with a premeasured
amount of oil (410ml for newer bikes?). Try not to spill any. I use a big injector like used for
marinating. Close the tops and bounce it a little to remove air and your good to go!

[Rick G]

I usually pull mine out as it gives me a chance to do a good clean and paint the lowers, they usually need it.

[frankenduck]

Consider removing the front wheel and draining the forks by removing the big hex bolts that screw up from the bottom. There's no chance you'll strip those.

That's not exactly true.  There are some models of K forks that have a shallow Allen head bolt there and the head will strip when you attempt to remove it. I've had it happen to me, even when being extremely careful. On top of that that particular  bolt is no longer available from BMW.

[TimTyler]

Right. I guess I was thinking about the threads.

Now that you mention it, I recall having to drill off one of those heads when I rebuilt my 3/91 forks last year because it had been stripped by a previous owner. I was able to get replacement bolts from the dealer, although a regular deep-head bolt can be used on one of the fork legs since the axle is not as thick on one side.

[Motorandy123]

I had the same problem with my 2007 F650GS. The heads are short and they
are in there tight. Using air tools and a good hex bit helps. I would think
most / all conventinal forks have a similar bolt... 

[frankenduck]

if I ever have to deal with one of those again I'll probably flip it upside down in a vice and give it a little Kroil bath ahead of time.

[Inge K.]

Also the correct tool, that won`t slip that easy.....helps.



Inge K.

[frankenduck]

When I run across bolts that I suspect will be a challenge I always use the ones from the OEM tool kit and make sure that they are well-seated.  then Kroil, then heat with torch.

[Motorandy123]

The problem is holding pressure on it while turning. Mine jumped out of the head
and spun. As I was pushing down against the spring. I got new bolts from BMW
and they were cheesier than the originals!

[Uffda]

Helpful tips from everyone.  thanks!  I plan to simply do a fluid change, leaving the forks in, etc.  Clymers manual says to hold the spring retainer with a 22mm wrench while using a hex wrench to loosen the fill plug.  What looks like the spring retainer is recessed, so I can't get a wrench on it, the recess is too tight to allow an adjustable wrench to effectively grab it, and it only has two flats that appear to be 17mm wide.  Picture attached.  A brief attempt to use the small  crescent wrench convinced me that I would only succeed in destroying the flats on the spring retainer.  It is essentially out of my reach.  :hmm:
Does this require a dedicated wrench to fit in the small recess and grab the flats?  Sure would like to get the fork oil changed before heading down to Virginia on Friday.

[Motorandy123]

The whole plug is held by a tiny metal ring. Get a gear puller and push down the plug
then pry the metal ring out. Do one side at a time. Remove the whole plug and do your
thing. It a bit easier as the hole is bigger.

[johnny]

greetings...

im very familiar with the hex spring retainer and fill plug on the 11 hundert motobrick...

however on my 75 flat track motobrick i see there is no hex spring retainer...

so my question is... pop the cover off and there should be a allen bolt in there like the in the photo with the red arrow... so its a matter of removing that bolt to filler up... nothing else... is that right...

yes i used the search button and yes i can read...

thank you in advance...

j o 

[The Mighty Gryphon]

You are correct, Johnny.  The allen head plug comes out to help the draining and refill the leg.  Sometimes(actually most of  the time) the cap that the allen screw is in will turn with the screw.  Hold it with an open end wrench while turning the allen screw.  It wasn't as hard for me as the previous posters made it sound.

For filling, I got a 2 foot piece of 5/16" vinyl hose and a piece of brass tube the fits in the end of the hose snugly.  A small funnel on the other end of the hose to pour the fork fluid in.  Heat the fluid in the microwave until it;s about 130 degrees and it will flow almost like water.  Takes about a minute to fill the tube without spilling a drop.

[johnny]

thanks... gonna charge the forks with antifreeze for the ice racing season...

[Elipten]

On my K75 I found the Allen head plug was put in by the crazy Germans with loctite.  I mean really for that application.  So a heat gun was needed to get it out.


2014 CB1100 DLX
2013 CB1100 Std
1990 BMW K75 RT

[johnny]

rodger that... will take it to the range and put some rounds in there if it wont turn...